| Value | Category | Cases | |
|---|---|---|---|
| 1 | 1 yr or less | 117 |
7%
|
| 2 | between 1 and 2 yrs | 83 |
5%
|
| 3 | more than 2 yrs | 199 |
11.9%
|
| 4 | never | 1261 |
75.6%
|
| 77 | don't know | 8 |
0.5%
|
| Sysmiss | 1296 |