| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 1 |
3%
|
| 0 | 28 |
84.8%
|
|
| 10 | 1 |
3%
|
|
| 20 | 1 |
3%
|
|
| 30 | 1 |
3%
|
|
| 40 | 1 |
3%
|
|
| Sysmiss | 1267 |