| Value | Category |
|---|---|
| 1 | Less than one week |
| 2 | One week or more but less than one month |
| 3 | One month or more but less than three months |
| 4 | Three months or more but less than six months |
| 5 | Six months or more but less than one year |
| 6 | One year or more but less than two years |
| 7 | Two years or longer |
| 8 | No definite length |
| Sysmiss |