Table 1.

Survey population composition

	N	%
Gender
Male	1516	52.64
Female	1314	47.36
Age(year)
6	359	12.47
7	416	14.44
8	322	11.18
9	583	20.24
10	333	11.56
11	416	14.44
12	451	15.66
Area
Han	2004	69.58
Man	728	25.28
Other	148	5.14