| Value | Category | Cases | |
|---|---|---|---|
| 1970 | 6 | 
                                                                 
                                    
                                    0%
                                 
                                                             | 
                                                        
                    |
| 1971 | 6 | 
                                                                 
                                    
                                    0%
                                 
                                                             | 
                                                        
                    |
| 1972 | 20 | 
                                                                 
                                    
                                    0.1%
                                 
                                                             | 
                                                        
                    |
| 1973 | 30 | 
                                                                 
                                    
                                    0.2%
                                 
                                                             | 
                                                        
                    |
| 1974 | 65 | 
                                                                 
                                    
                                    0.4%
                                 
                                                             | 
                                                        
                    |
| 1975 | 83 | 
                                                                 
                                    
                                    0.6%
                                 
                                                             | 
                                                        
                    |
| 1976 | 110 | 
                                                                 
                                    
                                    0.7%
                                 
                                                             | 
                                                        
                    |
| 1977 | 157 | 
                                                                 
                                    
                                    1.1%
                                 
                                                             | 
                                                        
                    |
| 1978 | 207 | 
                                                                 
                                    
                                    1.4%
                                 
                                                             | 
                                                        
                    |
| 1979 | 268 | 
                                                                 
                                    
                                    1.8%
                                 
                                                             | 
                                                        
                    |
| 1980 | 358 | 
                                                                 
                                    
                                    2.4%
                                 
                                                             | 
                                                        
                    |
| 1981 | 331 | 
                                                                 
                                    
                                    2.2%
                                 
                                                             | 
                                                        
                    |
| 1982 | 329 | 
                                                                 
                                    
                                    2.2%
                                 
                                                             | 
                                                        
                    |
| 1983 | 404 | 
                                                                 
                                    
                                    2.7%
                                 
                                                             | 
                                                        
                    |
| 1984 | 377 | 
                                                                 
                                    
                                    2.5%
                                 
                                                             | 
                                                        
                    |
| 1985 | 410 | 
                                                                 
                                    
                                    2.8%
                                 
                                                             | 
                                                        
                    |
| 1986 | 427 | 
                                                                 
                                    
                                    2.9%
                                 
                                                             | 
                                                        
                    |
| 1987 | 422 | 
                                                                 
                                    
                                    2.8%
                                 
                                                             | 
                                                        
                    |
| 1988 | 450 | 
                                                                 
                                    
                                    3%
                                 
                                                             | 
                                                        
                    |
| 1989 | 485 | 
                                                                 
                                    
                                    3.3%
                                 
                                                             | 
                                                        
                    |
| 1990 | 530 | 
                                                                 
                                    
                                    3.6%
                                 
                                                             | 
                                                        
                    |
| 1991 | 473 | 
                                                                 
                                    
                                    3.2%
                                 
                                                             | 
                                                        
                    |
| 1992 | 518 | 
                                                                 
                                    
                                    3.5%
                                 
                                                             | 
                                                        
                    |
| 1993 | 531 | 
                                                                 
                                    
                                    3.6%
                                 
                                                             | 
                                                        
                    |
| 1994 | 567 | 
                                                                 
                                    
                                    3.8%
                                 
                                                             | 
                                                        
                    |
| 1995 | 551 | 
                                                                 
                                    
                                    3.7%
                                 
                                                             | 
                                                        
                    |
| 1996 | 570 | 
                                                                 
                                    
                                    3.8%
                                 
                                                             | 
                                                        
                    |
| 1997 | 542 | 
                                                                 
                                    
                                    3.6%
                                 
                                                             | 
                                                        
                    |
| 1998 | 617 | 
                                                                 
                                    
                                    4.1%
                                 
                                                             | 
                                                        
                    |
| 1999 | 596 | 
                                                                 
                                    
                                    4%
                                 
                                                             | 
                                                        
                    |
| 2000 | 693 | 
                                                                 
                                    
                                    4.6%
                                 
                                                             | 
                                                        
                    |
| 2001 | 582 | 
                                                                 
                                    
                                    3.9%
                                 
                                                             | 
                                                        
                    |
| 2002 | 611 | 
                                                                 
                                    
                                    4.1%
                                 
                                                             | 
                                                        
                    |
| 2003 | 649 | 
                                                                 
                                    
                                    4.4%
                                 
                                                             | 
                                                        
                    |
| 2004 | 605 | 
                                                                 
                                    
                                    4.1%
                                 
                                                             | 
                                                        
                    |
| 2005 | 601 | 
                                                                 
                                    
                                    4%
                                 
                                                             | 
                                                        
                    |
| 2006 | 551 | 
                                                                 
                                    
                                    3.7%
                                 
                                                             | 
                                                        
                    |
| 2007 | 121 | 
                                                                 
                                    
                                    0.8%
                                 
                                                             | 
                                                        
                    |
| 9997 | Inconsistent | 5 | 
                                                                 
                                    
                                    0%
                                 
                                                             | 
                                                        
                    
| 9998 | Don't know year | 47 | 
                                                                 
                                    
                                    0.3%
                                 
                                                             | 
                                                        
                    
| 9999 | 4 |