Table 1.

Demographics of Study Sample (N = 69,891)

	Frequency
Variable	n	%
Gender
Male	48,168	68.9
Female	21,723	31.1
Ethnicitya
Caucasian	46,910	69.2
African American	20,393	30.1
Other	495	0.7
Ageb
<18	6,955	10.0
18–24	10,701	15.3
25–34	20,671	29.6
35–44	21,893	31.3
45–54	8,266	11.8
≥ 55	1,404	2.0
Residential Area
Urban	35,062	50.2
Rural	34,829	49.8
Year Admitted to Treatment
1998	9,911	14.2
1999	9,123	13.1
2000	9,598	13.7
2001	10,214	14.6
2002	9,891	14.2
2003	10,738	15.4
2004	10,416	14.9

^a2,093 missing ethnicity responses were removed from the total N for ethnicity percentages.

^b1 missing age response.