| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 6 |
20.7%
|
| 0 | None | 19 |
65.5%
|
| 1 | 3 |
10.3%
|
|
| 6 | 1 |
3.4%
|
|
| Sysmiss | 276 |