A new government survey finds 18.9 million people ages 12 and older—7.1 percent—misused prescription drugs such as pain relievers, tranquilizers, stimulants and sedatives last year.

The survey found 45 percent of Americans take one or more of these drugs, NPR reports. The widespread use of these drugs could be contributing to the high rate of misuse, experts say.

Most people who misused prescription drugs obtained them from friends and family, the survey found. More than one-third had their own prescription, but took more drugs than prescribed.

“Just like any drug, the more it’s out there, the more it’s available, the more likely it is to be abused,” Kim Johnson, Director of the Center for Substance Abuse Treatment at the Substance Abuse and Mental Health Services Administration, told NPR.