| Value |
Category |
| 1 |
1. Per month |
| 2 |
2. Per semester |
| 3 |
3. Per year |
| 5 |
5. Others |
| 6 |
6. None |
| 9 |
9. Missing |
| Sysmiss |
|
Warning: these figures indicate the number of cases found in the data file. They cannot be interpreted as summary statistics of the population of interest.