Table 1 Baseline characteristics of the study participants
| Â | Male | Female | Total | |||
|---|---|---|---|---|---|---|
n = 34,582 | n = 29,570 | n = 64,152 | ||||
n | % | n | % | n | % | |
School grade | ||||||
 Junior high school (12–15 y/o) | ||||||
  Grade 7 | 3740 | 10.8 | 3644 | 12.3 | 7384 | 11.5 |
  Grade 8 | 3687 | 10.7 | 3642 | 12.3 | 7329 | 11.4 |
  Grade 9 | 3702 | 10.7 | 3713 | 12.6 | 7415 | 11.6 |
 High school (15–18 y/o) | ||||||
  Grade 10 | 7963 | 23.0 | 6238 | 21.1 | 14,201 | 22.1 |
  Grade 11 | 7903 | 22.9 | 6309 | 21.3 | 14,212 | 22.2 |
  Grade 12 | 7470 | 21.6 | 5934 | 20.1 | 13,404 | 20.9 |
  Unknown | 117 | 0.3 | 90 | 0.3 | 207 | 0.3 |
 Municipality size groups | ||||||
  Large cities | 5551 | 16.1 | 5968 | 20.2 | 11,519 | 18.0 |
  Cities with populations ≥300,000 | 10,203 | 29.5 | 7288 | 24.6 | 17,491 | 27.3 |
  Cities with populations ≥100,000 | 11,049 | 32.0 | 9339 | 31.6 | 20,388 | 31.8 |
  Cities with populations < 100,000 | 5995 | 17.3 | 5168 | 17.5 | 11,163 | 17.4 |
  Smaller towns and villages | 1784 | 5.2 | 1807 | 6.1 | 3591 | 5.6 |
 Having breakfast | ||||||
  Every day | 28,070 | 81.2 | 25,192 | 85.2 | 53,262 | 83.0 |
  Sometimes | 3079 | 8.9 | 2600 | 8.8 | 5679 | 8.9 |
  Seldom | 2169 | 6.3 | 1321 | 4.5 | 3490 | 5.4 |
  Unknown | 1264 | 3.7 | 457 | 1.5 | 1721 | 2.7 |
 Participating in club activities | ||||||
  Active | 20,106 | 58.1 | 16,136 | 54.6 | 36,242 | 56.5 |
  Passive | 4667 | 13.5 | 4232 | 14.3 | 8899 | 13.9 |
  Not engaging | 8477 | 24.5 | 8646 | 29.2 | 17,123 | 26.7 |
  Unknown | 1332 | 3.9 | 556 | 1.9 | 1888 | 2.9 |