In Australia they found the same as in Canada, Washington, and Colorado: if you want fewer teens to smoke marijuana, then legalize!
Age-related trends in cannabis use in Australia. Findings from a series of large nationally representative surveys
• There is a diverging trend of cannabis use between the younger and older age groups.
• Prevalence of abstinence among the 55–74 year-olds decreased from 99% to 95%.
• Prevalence of abstinence among the 14–17 year-olds substantially increased from 79% to 92%.
Click here to read the study: https://doi.org/10.1016/j.addbeh.2021.107059
And this recent study in the U.S. looked at legalization in 46 states between 1991 and 2015, finding no evidence of increases in adolescents reporting past 30-day marijuana use or heavy marijuana use associated with state medical marijuana law or operational medical marijuana dispensaries.