| Value | Category | Cases | |
|---|---|---|---|
| 1 | mandatory | 219 |
3.8%
|
| 2 | voluntary | 897 |
15.7%
|
| 3 | both | 16 |
0.3%
|
| 4 | none | 4576 |
80.2%
|
| Sysmiss | 777 |