| Value | Category | Cases | |
|---|---|---|---|
| 1 | No, no difficulty | 38168 |
98.4%
|
| 2 | Yes, some | 502 |
1.3%
|
| 3 | Yes, a lot | 79 |
0.2%
|
| 4 | Cannot see at all | 37 |
0.1%
|
| Sysmiss | 6066 |