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. Author manuscript; available in PMC: 2018 May 1.
Published in final edited form as: Drug Alcohol Depend. 2017 Mar 7;174:150–157. doi: 10.1016/j.drugalcdep.2017.01.025

Table 3A.

Age at first opportunity, among participants who ever had the opportunity (unweighted)

Marijuana Inhalants Hallucinogens Cocaine Meth Heroin Stimulants Analgesics Tranquilizers Ecstasy
% (n) <15 25.5 (301) 10.4 (39) 3.7 (28) 1.2 (8) 4.8 (16) 2.2 (2) 3.4 (31) 2.0 (14) 2.8 (14) 5.0 (32)
% (n) 15 to 17 59.0 (696) 34.7 (130) 41.5 (316) 25.0 (166) 36.4 (121) 27.5 (25) 32.6 (297) 41.9 (299) 32.1 (160) 39.3 (253)
% (n) 18 to 21 13.7 (162) 44.8 (168) 48.4 (369) 60.0 (399) 46.4 (154) 57.1 (52) 59.1 (539) 47.0 (335) 43.8 (218) 43.2 (278)
% (n) 22 or older 1.8 (21) 10.1 (38) 6.4 (49) 13.8 (92) 12.3 (41) 13.2 (12) 4.9 (45) 9.1 (65) 21.3 (106) 12.4 (80)
Total 100.0 (1180) 100.0 (375) 100.0 (762) 100.0 (665) 100.0 (332) 100.0 (91) 100.0 (912) 100.0 (713) 100.0 (498) 100.0 (643)
Mean (SD) 15.8 (2.1) 17.9 (2.9) 17.9 (2.1) 19.1 (2.2) 18.4 (2.5) 18.9 (2.3) 18.2 (2.1) 18.2 (2.3) 19.0 (2.8) 18.3 (2.7)