| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 16 |
1.6%
|
| -7 | Does not apply (spontaneous) | 59 |
5.8%
|
| 1 | Very easy | 78 |
7.7%
|
| 2 | Easy | 458 |
44.9%
|
| 3 | Difficult | 328 |
32.2%
|
| 4 | Very Difficult | 80 |
7.9%
|