Table I.

Demographic characteristics by age group

	Ages
	12-13 (n=100)*	14-15 (n=571)*	16-17 (n=776)*	18-25 (n=1,329)*	26+ (n=1,308)*
Mean Age (SD)	13 (0)	14.7 (0.46)	16.6 (0.49)	21.7 (1.76)	29.0 (1.64)
% MZ	24.0%	34.3%	37.5%	37.7%	36.7%
% Female	42.0%	51.6%	49.9%	50.9%	51.5%
Ever smoking
Total sample	39.0%	53.8%	70.4%	76.4%	76.2%
Males	41.4%	55.4%	73.8%	80.4%	81.1%
Females	35.7%	52.2%	66.9%	72.5%	71.7%
Categorical quantity smoked - None
Total sample	69.2%	64.2%	68.0%	74.1%	74.4%
Males	70.8%	58.8%	62.0%	71.4%	72.8%
Females	66.7%	69.5%	74.5%	76.9%	76.2%
Categorical quantity smoked - Light: 1-10 CPD
Total sample	30.8%	29.6%	18.0%	17.0%	16.9%
Males	29.2%	31.4%	18.8%	16.4%	16.0%
Females	33.3%	27.9%	17.0%	17.8%	17.8%
Categorical quantity smoked - Heavy: 11+ CPD
Total sample	no obs	6.2%	14.1%	8.9%	8.7%
Males	no obs	9.8%	19.2%	12.2%	11.3%
Females	no obs	2.6%	8.5%	5.3%	6.0%

Note:

^*n indicates number of individuals