| Value | Category |
|---|---|
| 1 | Refuse to answer |
| 2 | Cannot remember when I bought the line |
| 3 | Less than a month |
| 4 | 2-6 months |
| 5 | 6-12 months |
| 6 | 1-5 years |
| 7 | More than 5 years |
| 8 | Don't know |
| 9 | Refused to answer |
| 10 | Outlier set to missing |
| 11 | Inconsistency set to missing |
| 12 | Not applicable |