| Value | Category | Cases | |
|---|---|---|---|
| 1 | Less than 1 year | 28 |
31.1%
|
| 2 | Between 1 and 3 years | 24 |
26.7%
|
| 3 | More than 3 years | 31 |
34.4%
|
| 4 | Others | 7 |
7.8%
|
| Sysmiss | 956 |