For the first time, U.S. drivers killed in crashes in 2015 were more likely to have used drugs than alcohol, according to a new study.

The study found 43 percent of drivers tested in fatal crashes in 2015 had used a legal or illegal drug, compared with 37 percent who showed alcohol levels above a legal limit, Reuters reports.

Among drivers who died in crashes who tested positive for drugs, 36.5 percent had used marijuana, while 9.3 percent used amphetamines. The report was released by the Governors Highway Safety Association and the Foundation for Advancing Alcohol Responsibility, a nonprofit funded by distillers.

“People generally should get educated that drugs of all sorts can impair your driving ability,” said Jim Hedlund, a former official at the National Highway Traffic and Safety Administration, who wrote the report. “If you’re on a drug that does so, you shouldn’t be driving.”