| Value | Category | Cases | |
|---|---|---|---|
| 1 | Less than a year | 148 |
3.1%
|
| 2 | Years | 736 |
15.3%
|
| 3 | No specific period | 3484 |
72.4%
|
| 9 | Missing | 445 |
9.2%
|
| 98 | Not applicable | 0 |
0%
|
| Sysmiss | 4614 |