| Value | Category | Cases | |
|---|---|---|---|
| 1 | mandatory | 46 |
2.7%
|
| 2 | voluntary | 180 |
10.5%
|
| 3 | both | 4 |
0.2%
|
| 4 | none | 1488 |
86.6%
|
| Sysmiss | 4767 |