| Value | Category | Cases | |
|---|---|---|---|
| 1 | 1 year or less | 220 |
9.9%
|
| 2 | Between 1 and 2 years | 146 |
6.6%
|
| 3 | More than 2 years | 407 |
18.4%
|
| 4 | Never | 1430 |
64.6%
|
| 77 | Don't know | 12 |
0.5%
|
| Sysmiss | 1837 |