| Statistical items of survey | Characteristics | n | % |
| Age at time of survey | 6 | 20 | 20% |
| 7 | 20 | 20% | |
| 8 | 20 | 20% | |
| 9 | 20 | 20% | |
| 10 | 20 | 20% | |
| Sex | Male | 50 | 50% |
| Female | 50 | 50% |