| Value | Category | Cases | |
|---|---|---|---|
| 1 | a. Once per month or more often | 253 |
98.4%
|
| 2 | b. Once per every two months | 3 |
1.2%
|
| 3 | c. Once per every six months or year | 1 |
0.4%
|
| Sysmiss | 420 |