| Value | Category | Cases | |
|---|---|---|---|
| 1 | 1 year or less | 40 |
7%
|
| 2 | Between 1 and 2 years | 22 |
3.9%
|
| 3 | More than 2 years | 41 |
7.2%
|
| 4 | Never | 458 |
80.2%
|
| 77 | Don't know | 10 |
1.8%
|
| Sysmiss | 4867 |