| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 677 |
22.9%
|
| -7 | Does not apply (spontaneous) | 243 |
8.2%
|
| 1 | Very easy | 114 |
3.9%
|
| 2 | Easy | 991 |
33.5%
|
| 3 | Difficult | 592 |
20%
|
| 4 | Very difficult | 338 |
11.4%
|