Table 1.

Prevalence of cannabis use at each time point estimated using all available data

	13 years	14 years	15 years	16 years	17 years	18 years
	n=4664	n=4571	n=4427	n=4196	n=3550	n=2939
Do not use	4525 (97.0%)	4470 (97.8%)	4032 (91.1%)	3782 (90.1%)	2868 (80.8%)	2457 (83.6%)
Occasional	139 (3.0%)	101 (2.2%)	275 (6.2%)	284 (6.8%)	533 (15.0%)	353 (12.0%)
Frequent	0 (0.0%)	0 (0.0%)	120 (2.7%)	130 (3.1%)	149 (4.2%)	129 (4.4%)

Derivation of the three categories used here is provided in online supplementary table S1.