| Value | Category | Cases | |
|---|---|---|---|
| 1 | Once a year | 346 |
60.5%
|
| 2 | Once in two years | 40 |
7%
|
| 3 | Once in three years | 85 |
14.9%
|
| 4 | Less than once in three years | 96 |
16.8%
|
| 77 | Don't know | 5 |
0.9%
|
| Sysmiss | 5441 |