| Value | Category | Cases | |
|---|---|---|---|
| 0 | neither certificate or registered | 16 |
26.2%
|
| 1 | has certificate | 39 |
63.9%
|
| 2 | registered | 5 |
8.2%
|
| 8 | don't know | 1 |
1.6%
|
| 11 | .Z | 15606 |