| Value | Category | Cases | |
|---|---|---|---|
| 0 | Neither certificate or registered | 28 |
40.6%
|
| 1 | Has certificate | 14 |
20.3%
|
| 2 | Registered | 25 |
36.2%
|
| 8 | DK | 2 |
2.9%
|
| Sysmiss | 8988 |