| Value | Category | Cases | |
|---|---|---|---|
| 1 | mandatory | 1 |
2.1%
|
| 2 | voluntary | 1 |
2.1%
|
| 3 | both | 0 |
0%
|
| 4 | none | 46 |
95.8%
|
| Sysmiss | 6437 |