If it seems like more people are smoking pot these days, you're not imagining it: According to a new study, the number of marijuana users has more than doubled since 2001.For the study , published earlier this week in JAMA Psychiatry, researchers looked at data from two nationally representative surveys of U.S. adults (adding up to nearly 80,000 participants). In the first survey, conducted between 2001 and 2002, 4.1% of respondents reported that they had used marijuana in the past year. But in the second one, conducted between 2012 and 2013, that number shot up to 9.5%. That means the number more than doubled in just a decade.Okay, there could be another issue going on here: Social mores are changing, and people may just feel more comfortable admitting their use these days than back in the early 2000s, when pot-smokers were more often thought of as losers and burnouts. But with such a large sample size, it's unlikely those stereotypes would really sway things this much.Researchers also looked at the prevalence of marijuana-use disorders (i.e. abuse or dependence as defined by the Diagnostic and Statistical Manual ) among those respondents who reported using pot. In the earlier survey, 35.6% of pot-using participants had met criteria for a marijuana-use disorder in the past year; that rate dropped to 30.6% in the second survey. Although this was a statistically significant difference, it's still a pretty small one. And it suggests that, in both surveys, about three in 10 people who use weed meet the criteria for abuse or dependence.While the majority of people who use marijuana don't become addicted to or dependent on it, there's still a risk. Figuring out just how big that risk is has proven to be extremely difficult . In these studies, though, it's reassuring that the prevalence of marijuana-use disorders didn't increase.So, as our attitudes and laws continue to loosen in order to give more people legal access to pot (medical and otherwise), the authors of this recent study want to make sure we don't forget that negative outcomes of marijuana use do exist. And if newly elected Canadian prime minister Justin Trudeau actually follows through on his eagerness to legalize marijuana , we should probably get our facts straight sooner rather than later.