Table1.

Frequency distribution of demographic characteristics(n = 975)

Variables	Groups	N	%
City	Jinzhou	636	65.23
	Dalian	339	34.77
Sex	Male	109	11.18
	Female	866	88.82
Age(years)	17	4	0.41
	18	57	5.82
	19	166	17.20
	20	283	29.33
	21	208	21.55
	22	164	16.99
	23	54	5.60
	24	22	2.28
	25	6	0.62
	26	1	0.10
Grade	Freshman	289	29.64
	Sophomore	412	42.26
	Junior	274	28.10
Only child	Yes	411	42.34
	No	562	57.76
Education	Higher vocational schools	298	30.56
	The third batch of undergraduate	182	18.67
	The second batch of undergraduate	495	50.77
place of residence	Urban	419	43.29
	Rural	452	46.69
	Suburban	97	10.02