| Value | Category | Cases | |
|---|---|---|---|
| 1 | a. Once per month or more often | 2955 |
98.1%
|
| 2 | b. Once per every two months | 49 |
1.6%
|
| 3 | c. Once per every six months or year | 7 |
0.2%
|
| Sysmiss | 1957 |