| Value | Category | Cases | |
|---|---|---|---|
| 0 | Neither certificate or registered | 552 |
37.1%
|
| 1 | Has certificate | 273 |
18.4%
|
| 2 | Registered | 625 |
42.1%
|
| 8 | Don't know | 36 |
2.4%
|
| 9 | 45 | ||
| Sysmiss | 34899 |