| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 12 |
1.2%
|
| -7 | Does not apply (spontaneous) | 24 |
2.4%
|
| 1 | Very easy | 329 |
32.3%
|
| 2 | Easy | 524 |
51.4%
|
| 3 | Difficult | 109 |
10.7%
|
| 4 | Very Difficult | 21 |
2.1%
|