| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 52 |
9.4%
|
| 1 | Higher than usual | 34 |
6.1%
|
| 2 | Lower than usual | 134 |
24.2%
|
| 3 | The usual | 334 |
60.3%
|