What Percentage of Americans Smoke Marijuana? January 31, 2020 In a July 2019 Gallup poll, 12% of U.S. adults said they smoke marijuana, a percentage that is essentially unchanged since 2015. CONT. Gallup Share:Click to share on Twitter (Opens in new window)Click to share on Facebook (Opens in new window)Click to share on Reddit (Opens in new window)Click to email a link to a friend (Opens in new window)Click to share on LinkedIn (Opens in new window)Click to share on Tumblr (Opens in new window)Click to share on Pinterest (Opens in new window)MoreClick to print (Opens in new window)