| Value | Category | Cases | |
|---|---|---|---|
| 1 | Less tha | 6 |
4.1%
|
| 2 | A month | 138 |
93.2%
|
| 3 | 6 to 12 | 4 |
2.7%
|
| 4 | over 12 | 0 |
0%
|
| Sysmiss | 2 |