| Value | Category | Cases | |
|---|---|---|---|
| 1 | mandatory | 147 |
3.6%
|
| 2 | voluntary | 579 |
14.1%
|
| 3 | both | 11 |
0.3%
|
| 4 | none | 3368 |
82%
|
| Sysmiss | 2380 |