| Value | Category | Cases | |
|---|---|---|---|
| 1 | Monthly | 149 |
6.2%
|
| 2 | Quarterly | 1693 |
70.4%
|
| 3 | Every semester | 226 |
9.4%
|
| 4 | Yearly | 338 |
14%
|
| Sysmiss | 644 |