| Value | Category | Cases | |
|---|---|---|---|
| 1 | 1 yr or less | 571 |
34.2%
|
| 2 | between 1 and 2 yrs | 253 |
15.2%
|
| 3 | more than 2 yrs | 471 |
28.2%
|
| 4 | never | 323 |
19.4%
|
| 77 | don't know | 50 |
3%
|
| Sysmiss | 1296 |