Santos Umar, director of the Global Drug Policy Reform Project and the lead researcher who led the study, said the researchers would now focus on better measuring how those drugs have changed in the U.S. and analyzing policy effects.

The researchers also want to find where the trends might be different in countries that currently have fewer restrictions on marijuana.

“Our paper really shows that we need an aggressive U.S. public health and policy effort in order to get an accurate picture of these trends,” the report reads.

The U.S. has made efforts since 2002 to discourage the drug, but the data shows that the rate of marijuana use has stabilized over that time.

However, experts say the steady growth in marijuana legalization shows that legalization does not necessarily equal harm.

“When you give people more choices they become more likely to use marijuana in the first place,” said Scott Faber, vice president of marijuana policy studies at the libertarian Cato Institute in Washington, D.C.

This map shows the states and territories where recreational marijuana is legal. Click on the state to make sure legalization has been legal there. (Image source: Marijuana Policy Project)

“States are allowed to have more latitude… which means marijuana that goes on the street or in a restaurant is going to be much less dangerous than if it was legalized or legalized by the federal government,” Faber said. “This is a very important point that needs to be communicated.”

But he’s not convinced that legalization will necessarily end up doing harm.

“You end up with this sort of ‘if you can’t prevent it, you don’t control it,'” he added.