| Value | Category | Cases | |
|---|---|---|---|
| 0 | very irregularly | 1656 |
17.4%
|
| 1 | less than 1 hour | 1079 |
11.3%
|
| 2 | between 1 and 2 hours | 2314 |
24.3%
|
| 3 | between 2 and 4 hours | 1941 |
20.4%
|
| 4 | more than 4 hours | 2544 |
26.7%
|
| Sysmiss | 5542 |