| Value | Category | Cases | |
|---|---|---|---|
| 1 | Quarterly | 1794 |
19.4%
|
| 2 | Annually | 4601 |
49.7%
|
| 3 | Once in every 2 years | 348 |
3.8%
|
| 4 | When got sick | 2066 |
22.3%
|
| 6 | Other | 448 |
4.8%
|
| Sysmiss | 4200 |