| Variable | % |
| Gender |
|
| Female | 50 |
| Male | 50 |
| Education of father |
|
| Primary school | 5 |
| High school | 40 |
| Professional qualification | 20 |
| Bachelor degree | 35 |
| Education of mother |
|
| Primary school | 5 |
| High school | 35 |
| Professional qualification | 20 |
| Bachelor degree | 40 |
| Relative income |
|
| Low | 35 |
| Middle | 55 |
| High | 10 |