| Value | Category | Cases | |
|---|---|---|---|
| 1 | Once every 2 years | 44 |
7.3%
|
| 2 | Once a year | 67 |
11.2%
|
| 3 | Twice a year | 181 |
30.2%
|
| 4 | More than twice a year | 307 |
51.3%
|