| Value | Category | Cases | |
|---|---|---|---|
| 1 | Once | 6635 |
91.9%
|
| 2 | Twice | 472 |
6.5%
|
| 3 | Three times | 68 |
0.9%
|
| 4 | Four times or more | 17 |
0.2%
|
| 98 | Don't know | 28 |
0.4%
|
| Sysmiss | 18222 |