| Value | Category |
|---|---|
| 1 | 1 day or less |
| 2 | Between 1 and 7 days |
| 3 | Between 1 week and 1 month |
| 4 | More than 1 month |
| a | Don't know |
| b | Refused to answer |
| c | Outlier set to missing |
| d | Dropped during anonymization (available on request) |
| e | Skipped in error |
| m | Not available in wave |
| z | Not applicable |