| Value | Category | Cases | |
|---|---|---|---|
| 1 | Less tha | 18 |
13.1%
|
| 2 | A month | 106 |
77.4%
|
| 3 | 6 to 12 | 12 |
8.8%
|
| 4 | over 12 | 0 |
0%
|
| 6 | 1 |
0.7%
|
|
| Sysmiss | 13 |