| Value | Category |
|---|---|
| 1 | Within the last week = 1 |
| 2 | Within the last month = 2 |
| 3 | Within the last 3 months = 3 |
| 4 | Within the last 6 months - 4 |
| 5 | Within the last year = 5 |
| 6 | More than 1 year ago = 6 |
| 7 | Never = 7 |
| 97 | Not applicable = 97 |
| 98 | Dont know = 98 |
| 99 | Missing = 99 |
| Sysmiss |