| Value | Category | Cases | |
|---|---|---|---|
| 0 | Neither certificate or registered | 7 |
43.8%
|
| 1 | Has certificate | 4 |
25%
|
| 2 | Registered | 3 |
18.8%
|
| 8 | DK | 2 |
12.5%
|
| 9 | 2 | ||
| Sysmiss | 9039 |