| Value | Category | Cases | |
|---|---|---|---|
| 1 | 1 yr or less | 271 |
27.2%
|
| 2 | between 1 and 2 yrs | 137 |
13.8%
|
| 3 | more than 2 yrs | 148 |
14.9%
|
| 4 | never | 401 |
40.3%
|
| 77 | don't know | 38 |
3.8%
|
| Sysmiss | 648 |