| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 75 |
27.7%
|
| 0 | 189 |
69.7%
|
|
| 10 | 3 |
1.1%
|
|
| 20 | 3 |
1.1%
|
|
| 30 | 1 |
0.4%
|