| Value | Category | Cases | |
|---|---|---|---|
| 1 | No, no difficulty | 13782 |
95.7%
|
| 2 | Yes, some difficulty | 540 |
3.7%
|
| 3 | Yes, a lot of difficulty | 75 |
0.5%
|
| 4 | Yes, cannot see at all | 4 |
0%
|
| Sysmiss | 1891 |