| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 0 |
0%
|
| 0 | 16 |
80%
|
|
| 15 | 1 |
5%
|
|
| 20 | 2 |
10%
|
|
| 40 | 1 |
5%
|
|
| Sysmiss | 91 |