| Value | Category | Cases | |
|---|---|---|---|
| 1 | Water seal | 13957 |
78.5%
|
| 2 | Pour flush | 2796 |
15.7%
|
| 3 | Pit | 996 |
5.6%
|
| 4 | Other (specify) | 0 |
0%
|
| 9 | 23 |
0.1%
|
|
| Sysmiss | 772 |