demonstrator smoking giant joint
A demonstrator smokes a giant cannabis cigarette during a pro-marijuana legalization march in Brasilia, Brazil, May 23, 2014. Reuters/Ueslei Marcelino

Cannabis use in the U.K. has almost halved over the past decade, even as marijuana use among 15- to 34-year-olds has grown throughout most of the Europe, according to the annual report by the European Monitoring Centre for Drugs and Drug Addiction released Thursday. As Brits are increasingly turning down pot, nations across Europe and states in the United States have begun decriminalizing marijuana-related offenses and use of the drug.

The decreased use of pot in the U.K. came as something of a surprise to researchers. In 2003, roughly 19 percent of British 15- to 34-year-olds used cannabis, but only about 11 percent consumed marijuana in 2013, according to the report.

Alex Stevens, a professor of criminal justice at the University of Kent, suggested to the Economist that the decrease in pot usage in the U.K. might be due to the rise of high-strength "skunk" grown in Britain instead of milder cannabis resin from North Africa. The drop in marijuana use could also be attributed to a general decline of smoking in the nation, especially since pot and tobacco are frequently combined in Britain.

At the same time, the price of pot in the U.K. has nearly doubled over the past 10 years and is now roughly two-thirds more expensive than marijuana sold in, say, Spain, the Independent reported. Meanwhile, the rising use of cocaine in the country has likely taken users away from cannabis.

Across Europe, marijuana is still the most popular drug, with almost 79 million EU citizens estimated to have tried marijuana. The United States, Canada, Nigeria and Australia have the most marijuana users in the world, according to the United Nations. The countries with the least pot smokers were Ecuador, Paraguay, Turkey and Romania, the Daily Mail reported.