The percentage of Americans who say they currently smoke marijuana has nearly doubled since 2013, a new survey finds.

Thirteen percent of adults in the U.S. now say they currently smoke pot — up from 7 percent in 2013, according to the new Gallup poll.

The percentage of Americans who said they had ever tried marijuana also increased since 2013. This year, 43 percent of Americans said they had tried the drug — up from 38 percent in 2013, according to the poll. [Where Americans Smoke and Grow Marijuana (Maps)]

Recreational marijuana use is legal in four states (Colorado, Washington, Alaska and Oregon) and the District of Columbia. In addition, half of U.S. states have some version of a medical marijuana law, according to Gallup. In November, four more states will vote on whether to allow medical marijuana.

People's age and religiousness played key roles in whether they had ever tried marijuana, the Gallup researchers found. Nearly 1 in 5 U.S. adults under age 30 said they currently use marijuana, according to the poll. In each of the older age groups the researchers looked at, no more than 1 in 10 people said they currently use marijuana.

However, more adults ages 30 to 49 and 50 to 64 said they had ever tried marijuana than adults ages 18 to 29. Nearly half of the adults ages 30 to 64 had tried the drug at least once in their life, whereas only 38 percent of people ages 18 to 29 reported having tried marijuana, the researchers found. The older groups may have been more likely to have tried the drug simply because they've had more years to do so, or because attitudes toward marijuana have changed over time, the researchers wrote.

Americans who said they attend church weekly were much less likely to smoke marijuana than those who said they rarely or never attend church: Only 2 percent of weekly churchgoers said they currently smoke marijuana, compared with 14 percent of those who said they do not go to church, according to the poll.

Adults in the western U.S. were more likely to report that they currently smoke marijuana compared with adults in the eastern, Midwest and southern U.S., according to the poll. (A survey from July found that marijuana use was particularly high in San Francisco and Denver compared with the rest of the country.)

The results are based on telephone interviews with more than 1,000 adults in all 50 states and the District of Columbia. The interviews were conducted July 13-17, 2016.

Originally published on Live Science.

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