| Value | Category | Cases | |
|---|---|---|---|
| 1 | mandatory | 83 |
3%
|
| 2 | voluntary | 339 |
12.4%
|
| 3 | both | 5 |
0.2%
|
| 4 | none | 2296 |
84.3%
|
| Sysmiss | 3762 |