| Value | Category | Cases | |
|---|---|---|---|
| 0 | neither certificate or registered | 238 |
1.8%
|
| 1 | has certificate | 0 |
0%
|
| 2 | registered | 12667 |
95.9%
|
| 6 | other | 127 |
1%
|
| 8 | don't know | 177 |
1.3%
|
| Sysmiss | 149250 |