| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 11 |
1.1%
|
| -7 | Does not apply (spontaneous) | 21 |
2.1%
|
| 1 | Very easy | 353 |
34.6%
|
| 2 | Easy | 516 |
50.6%
|
| 3 | Difficult | 105 |
10.3%
|
| 4 | Very Difficult | 13 |
1.3%
|