| Value | Category |
|---|---|
| -99 | N/A |
| -98 | Don't Know |
| -97 | Declined |
| 1 | 15-19 |
| 2 | 20-24 |
| 3 | 25-29 |
| 4 | 30+ |
| 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 |