| Value | Category |
|---|---|
| 1 | Unaware of the process |
| 3 | Do not trust that data will be kept confidential |
| 4 | See no benefit in registration |
| 5 | Waiting for registration |
| 7 | Distance or difficulty of reaching the registration centre |
| 96 | Other (specify) |
| 97 | N/A |
| 98 | DK |
| Sysmiss |