| Value | Category |
|---|---|
| 1 | 1â3 months |
| 2 | 4â6 months |
| 3 | 7â12 months |
| 4 | 13â24 months |
| 5 | 25â49 months |
| 6 | 50+ months |
| a | Don't know |
| b | Refused to answer |
| c | Outlier set to missing |
| d | Dropped during anonymization (available on request) |
| e | Skipped in error |
| z | Not applicable |