| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 1 |
25%
|
| 0 | 1 |
25%
|
|
| 2 | 1 |
25%
|
|
| 4 | 1 |
25%
|
|
| Sysmiss | 107 |