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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 1.

Opportunity to use, use, and use given opportunity by drug and study year

Marijuana Prescription
Stimulants		 Hallucinogens Prescription
Analgesics		 Cocaine Ecstasy Prescription Tranquilizers Inhalants Heroin Amphetamines Methamphetamine
n %wt n %wt n %wt n %wt n %wt n %wt n %wt n %wt n %wt n %wt n %wt
%wt Opportunity
 Year 2 922 70.9 522 38.7 385 24.8 311 20.3 299 18.8 211 14.3 153 9.4 102 6.2 18 1.3 - - - -
 Year 3 881 70.3 509 41.5 334 24.2 293 21.9 332 22.0 234 17.3 168 11.5 90 6.1 23 1.6 65 5.0 20 1.4
 Year 4 844 68.4 404 32.5 337 24.5 212 14.6 336 23.8 223 16.6 144 9.6 79 6.0 13 1.1 35 3.0 6 0.3
 Year 5 710 61.3 313 27.1 249 20.1 167 13.0 280 20.9 165 12.7 131 10.2 59 4.3 11 1.0 33 2.8 12 0.9
 Year 6 631 55.0 202 16.4 172 14.5 134 10.7 231 18.2 144 12.0 128 10.1 44 3.8 8 0.5 25 2.0 13 1.0
 Year 7 558 49.4 160 12.9 148 12.4 111 9.5 206 16.4 140 11.4 91 7.1 44 3.6 6 0.5 19 1.7 3 0.3
 Year 8 523 48.2 144 12.0 117 9.8 75 6.8 174 14.3 122 9.9 79 6.0 29 2.6 3 0.3 11 1.1 7 0.8
%wt Use
 Year 2 695 45.8 281 17.9 137 7.9 168 10.2 106 5.8 38 2.0 73 4.3 46 2.8 2 0.1 - - - -
 Year 3 654 46.9 304 20.5 120 8.3 157 10.3 146 8.7 60 3.6 104 6.9 35 2.1 6 0.5 8 0.6 2 0.1
 Year 4 598 44.4 235 16.8 114 8.1 124 8.8 141 9.0 59 4.1 82 5.4 36 2.6 2 0.2 3 0.2 0 0.0
 Year 5 481 37.7 184 13.9 103 7.8 100 7.7 115 7.7 52 3.4 71 4.6 31 2.3 0 0.0 2 0.2 1 0.1
 Year 6 401 32.8 131 9.8 81 6.2 84 6.4 88 6.1 53 4.3 70 5.1 18 1.7 2 0.1 1 0.1 1 0.1
 Year 7 370 31.1 106 8.2 57 4.4 71 5.4 72 4.9 58 4.3 53 3.9 26 2.3 2 0.1 1 0.1 0 0.0
 Year 8 332 28.6 84 6.6 61 5.5 45 3.5 82 5.8 60 4.6 37 2.5 19 1.8 0 0.0 2 0.1 0 0.0
% Use Given Opportunity n % n % n % n % n % n % n % n % n % n % n %
 Year 2 692 75.1 234 44.8 130 33.8 142 45.8 104 34.8 36 17.1 68 44.7 40 39.2 2/18 11.1 - - - -
 Year 3 651 73.9 252 49.5 112 33.5 133 45.4 143 43.1 58 24.8 91 54.2 30 33.3 6/23 26.1 6/65 9.2 2/20 10.0
 Year 4 590 69.9 179 44.3 111 32.9 99 46.7 140 41.7 56 25.1 72 50.0 34 43.0 1/13 7.7 3/35 8.6 0/6 0.0
 Year 5 476 67.0 149 47.6 95 38.2 70 41.9 114 40.7 51 30.9 61 46.6 29 49.2 0/11 0.0 1/33 3.0 1/12 8.3
 Year 6 395 62.6 107 53.0 76 44.2 65 48.5 86 37.2 51 35.4 61 47.7 17/44 38.6 1/8 12.5 1/25 4.0 1/13 7.7
 Year 7 362 64.9 82 51.3 54 36.5 55 49.5 72 35.0 58 41.4 43 47.3 21 47.7 2/6 33.3 1/19 5.3 0/3 0.0
 Year 8 323 61.8 67 46.5 56 47.9 33 44.0 79 45.4 57 46.7 33 41.8 17/29 58.6 0/3 0.0 2/11 18.2 0/7 0.0

Note. Opportunity and use percentages are weighted (%wt) for sampling and attrition, and use given opportunity values are unweighted. All n’s are unweighted. Use given opportunity estimates represent the percentage of the sample who had the opportunity to and used a drug within a given study year. Prescription stimulants, analgesics, and tranquilizers refer to nonmedical use. Years 2 through 8 correspond to modal ages 19 through 25, respectively. Results based on small denominators (n<20) are reported as fractions rather than percentages.