Table 1.

The Characteristics of the Samples

	Total		Boys		Girls
	n	%	n	%	n	%
Total	50,090	100	25,244	50.4	24,846	49.6
Age Groups***
Younger adolescents	14,552	29.1%	7486	29.7%	7066	28.4%
Adolescents	21,879	43.7%	11,088	43.9%	10,791	43.4%
Older adolescents	13,659	27.3%	6670	26.4%	6989	28.1%

Younger adolescents: 4-5th graders

Adolescents: 6-9th graders

Older adolescents: 10-12th graders

Significance difference at genders at p < 0.001

*p < 0.05, **p < 0.01, ***p < 0.001