| Value | Category | Cases | |
|---|---|---|---|
| 1 | No difficulty | 2594184 |
96%
|
| 2 | Yes, some difficulty | 91209 |
3.4%
|
| 3 | Yes, a lot of difficulty | 12163 |
0.5%
|
| 4 | Cannot see at all | 3489 |
0.1%
|
| Sysmiss | 383938 |