France and Canada have the highest percentage of 15-year-old pot smokers among 42 well-off nations surveyed by the World
Health Organization, the UN agency said in a report Tuesday.
When it comes to policing marijuana, France is far from the most laid-back country in Europe, so the findings come as something of a surprise.
Amsterdam flaunts its cannabis cafes and Barcelona its private reefer clubs, but neither the Netherlands nor Spain were among the top eight nations in which teens admitted they had used cannabis in the last 30 days, according to the study, based on data from 2014.
Fifteen percent of 15-year-olds in France -- slightly more boys than girls -- said they had indulged, with Canada's young stoners close behind.
Italy, Switzerland and Bulgaria rounded out the top five, with French-speaking parts of Belgium as well as Poland and Slovenia in low double digits for boys, and single digits for girls.
"Young people in their teenage years are more likely to use cannabis if they have friends or older siblings who do so," the study found.
Lax parenting or its opposite -- "coercive discipline" -- also correlated with higher rates of marijuana consumption.
Conducted every four years, the WHO survey examines risky behaviour and self-perception among 11-, 13- and 15-year olds in Europe, North America and Israel.
In the most recent survey, France dislodged Canada as No. 1 nation for teen tokers, moving up from fourth place.
The United States ranked second in the 2010 survey but was not included in the most recent edition.
Among the countries with the fewest adolescent users was Sweden, with only two percent of 15-year-olds saying they had gotten high on ganja in the last month.
"Scientific evidence proves that cannabis is a dangerous and harmful substance, especially for children and young people who use it regularly," the study notes.
Marijuana is the most used drug in Europe, with 14.6 million young adults lighting up in 2014, according the report.
About a dozen countries in Europe have provisions for the medical use of marijuana, including Austria, Britain, France, Germany, Italy, the Netherlands, Portugal and Spain.