| Value | Category | Cases | |
|---|---|---|---|
| 0 | neither certificate or registered | 4 |
40%
|
| 1 | has certificate | 4 |
40%
|
| 2 | registered | 1 |
10%
|
| 8 | don't know | 1 |
10%
|
| 11 | .Z | 15657 |