| Value | Category | Cases | |
|---|---|---|---|
| 1 | 1. Per month | 58 |
65.9%
|
| 2 | 2. Per semester | 8 |
9.1%
|
| 3 | 3. Per year | 17 |
19.3%
|
| 5 | 5. Others | 5 |
5.7%
|
| 6 | 6. None | 0 |
0%
|
| 9 | 9. Missing | 0 |
0%
|
| Sysmiss | 251 |