| Value | Category | Cases | |
|---|---|---|---|
| 0 | no difficulty | 7900 |
96.5%
|
| 1 | Some difficulty | 186 |
2.3%
|
| 2 | Great difficulty | 74 |
0.9%
|
| 3 | Can not completely | 23 |
0.3%
|
| Sysmiss | 6 |