| Value | Category | Cases | |
|---|---|---|---|
| 1 | About one month | 1 |
4.8%
|
| 2 | Few months (2-3 months) | 1 |
4.8%
|
| 3 | Less than one year | 4 |
19%
|
| 4 | More than one year | 15 |
71.4%
|
| Sysmiss | 61 |