| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 0 |
0%
|
| 4 | 1 |
25%
|
|
| 6 | 1 |
25%
|
|
| 8 | 1 |
25%
|
|
| 15 | 1 |
25%
|
|
| Sysmiss | 356 |