| Value | Category | Cases | |
|---|---|---|---|
| 0 | Neither certificate or registered | 54 |
39.4%
|
| 1 | Has certificate | 28 |
20.4%
|
| 2 | Registered | 47 |
34.3%
|
| 8 | DK | 8 |
5.8%
|
| Sysmiss | 8920 |