| Value | Category | Cases | |
|---|---|---|---|
| 1 | Once every 2 years | 19 |
3.2%
|
| 2 | Once a year | 182 |
30.4%
|
| 3 | Twice a year | 348 |
58.1%
|
| 4 | More than twice a year | 50 |
8.3%
|