Between 2013 and 2019, by how much did the portion of adults in the U.S. who say they currently smoke marijuana increase?
In 2013, 7% of adults in the U.S. said they currently smoked marijuana. By 2019, this figure had grown to 12%, which is a 71% increase. Beyond survey data, other measures that are not dependent on the honesty of people, like drug test failure rates, also indicate that usage of marijuana has grown in recent years. With this, the average potency of marijuana has multiplied over recent decades. In 1980, the average THC content of seized marijuana was 1.2%. This rose to 4.2% in 1999 and 9.4% in 2017. THC is the psychoactive ingredient in marijuana, and higher levels of it may increase rates of addiction and mental health problems.