Table 1. Mean (Standard Deviation) of Marijuana Use and Proportions of Marijuana Users at Each Time Point from Adolescence to Mean Age 43 (N=548).

Time Points	Mean of Marijuana Use	Standard Deviation of Marijuana Use	Proportions of Marijuana Users
T2 (Mean age =14)	0.56	1.19	28.5%
T3 (Mean age =16)	0.75	1.35	33.5%
T4 (Mean age =21)	1.00	1.37	54.4%
T5 (Mean age =27)	0.94	1.43	46.7%
T6 (Mean age =32)	0.72	1.37	34.8%
T7 (Mean age =37)	0.61	1.23	31%
T8 (Mean age =43)	0.58	1.26	28.5%

Note: The marijuana use measure at each point in time had a scale coded as none (0), a few times a year or less (1), once a month (2), several times a month (3), once a week (4), several times a week (5), and daily (6).