| Value | Category | Cases | |
|---|---|---|---|
| -1 | Missing | 0 |
0%
|
| 1 | Very easy | 28 |
1.2%
|
| 2 | Easy | 154 |
6.4%
|
| 3 | Difficult | 773 |
32.2%
|
| 4 | Very difficult | 1173 |
48.9%
|
| 9 | Don't know | 269 |
11.2%
|