Equally remarkable as the consistent median AOO across countries is the age range of risk. Fully half the people who had ever used alcohol began using in the 7-y age range between 14–21 y. The interquartile range (IQR) (i.e., 25th–75th percentiles) of AOO distributions were typically 15–21 y for tobacco, 16–22 y for cannabis, and 19–28 y for cocaine.
