| Value | Category | Cases | |
|---|---|---|---|
| -1 | Missing | 0 |
0%
|
| 1 | Very easy | 40 |
1.7%
|
| 2 | Easy | 157 |
6.5%
|
| 3 | Difficult | 824 |
34.4%
|
| 4 | Very difficult | 1101 |
45.9%
|
| 9 | Don't know | 275 |
11.5%
|