| Value | Category | Cases | |
|---|---|---|---|
| 1 | mandatory | 1 |
1.6%
|
| 2 | voluntary | 1 |
1.6%
|
| 3 | both | 0 |
0%
|
| 4 | none | 62 |
96.9%
|
| Sysmiss | 6421 |