| Value | Category | Cases | |
|---|---|---|---|
| 1 | Once a year | 2203 |
2.8%
|
| 2 | Every six months | 25463 |
32.5%
|
| 3 | More often than once every 6 months | 37293 |
47.6%
|
| 5 | Deprecated (not in IQ2) | 5436 |
6.9%
|
| 6 | Don't know | 1183 |
1.5%
|
| 7 | Not applicable | 6331 |
8.1%
|
| 8 | Refused | 3 |
0%
|
| 9 | Missing | 443 |
0.6%
|