| Value | Category |
|---|---|
| 1 | One month |
| 2 | Two months |
| 3 | Three months |
| 4 | Four months |
| 5 | Five months |
| 6 | Half a year |
| 7 | More than half a year |
| 8 | 1 year |
| 9 | 2 years |
| 10 | 3 years |
| 11 | More than 3 years |
| 2147483622 | Don't know |
| 2147483623 | Refused to respond |
| 2147483647 | Not Applicable |
| 101 | .Z |