| Value | Category | Cases | |
|---|---|---|---|
| 1 | Very easy | 493 |
2.7%
|
| 2 | Easy | 1660 |
9.1%
|
| 3 | Difficult | 5102 |
28.1%
|
| 4 | Very difficult | 6989 |
38.5%
|
| 5 | Don't know | 3912 |
21.5%
|