| Value | Category | Cases | |
|---|---|---|---|
| -1 | Missing | 0 |
0%
|
| 1 | Very easy | 155 |
6.5%
|
| 2 | Easy | 306 |
12.8%
|
| 3 | Difficult | 910 |
37.9%
|
| 4 | Very difficult | 838 |
34.9%
|
| 9 | Don't know | 191 |
8%
|