| Value | Category | Cases | |
|---|---|---|---|
| 1 | No difficulty | 2646725 |
98%
|
| 2 | Yes, some difficulty | 43874 |
1.6%
|
| 3 | Yes, a lot of difficulty | 8839 |
0.3%
|
| 4 | Cannot remember or concentrate at all | 1607 |
0.1%
|
| Sysmiss | 383938 |