| Value | Category | Cases | |
|---|---|---|---|
| 0 | neither certificate or registered | 30 |
16.5%
|
| 1 | has certificate | 28 |
15.4%
|
| 2 | registered | 123 |
67.6%
|
| 8 | don't know | 1 |
0.5%
|
| Sysmiss | 12767 |