| Value | Category | Cases | |
|---|---|---|---|
| 1 | At once | 518 |
32.3%
|
| 2 | Within a month | 161 |
10%
|
| 3 | Later than a month | 102 |
6.4%
|
| 4 | Don't know | 823 |
51.3%
|
| Sysmiss | 2940 |