| Value | Category | Cases | |
|---|---|---|---|
| 0 | neither certificate or registered | 33 |
35.1%
|
| 1 | has certificate | 49 |
52.1%
|
| 2 | registered | 9 |
9.6%
|
| 8 | don't know | 2 |
2.1%
|
| 9 | 1 |
1.1%
|
|
| Sysmiss | 815 |