Differences in illegal drug use were more marked among young adults: by age 15 y, those in New Zealand (27%) and the US (20%) had the highest levels of cannabis use, with almost no use in Asia, Middle East, or Africa among this cohort. Few young adults in the Netherlands had used cannabis by age 15 y (7%; Table 3). The majority of young adults in New Zealand (62%) and the US (54%) had used by age 21 y, compared to 35% of those in the Netherlands.
