| Value | Category | Cases | |
|---|---|---|---|
| 0 | neither certificate or registered | 3123 |
36.8%
|
| 1 | has certificate | 4320 |
51%
|
| 2 | registered | 859 |
10.1%
|
| 8 | don't know | 102 |
1.2%
|
| 9 | 71 |
0.8%
|
|
| Sysmiss | 68445 |