| Value | Category | Cases | |
|---|---|---|---|
| 0 | Never absent | 780 |
50.5%
|
| 1 | Less than 3 months | 564 |
36.5%
|
| 2 | 3-6 months | 153 |
9.9%
|
| 3 | 6-9 months | 18 |
1.2%
|
| 4 | More than 9 months | 29 |
1.9%
|
| Sysmiss | 5617 |