| Value | Category | Cases | |
|---|---|---|---|
| 1 | Water seal | 14941 |
76.8%
|
| 2 | Pour flush | 3812 |
19.6%
|
| 3 | Pit | 676 |
3.5%
|
| 4 | Other (specify) | 0 |
0%
|
| 9 | 15 |
0.1%
|
|
| Sysmiss | 514 |