| Value | Category | Cases | |
|---|---|---|---|
| 0 | Neither certificate or registered | 332 |
40.6%
|
| 1 | Has certificate | 200 |
24.4%
|
| 2 | Registered | 265 |
32.4%
|
| 8 | DK | 21 |
2.6%
|
| 9 | 18 | ||
| Sysmiss | 8221 |