As the nation takes a softer stance on marijuana, more Americans are using the drug, the National Survey on Drug Use and Health found.
The nationwide survey made public Wednesday found 7.3% of Americans 12 or older regularly used marijuana in 2012, up from 7% in 2011. Marijuana use has increased steadily over the past five years. In 2007, the survey found 5.8% of Americans 12 or older used marijuana.
The report from the Substance Abuse and Mental Health Services Administration surveys 70,000 people aged 12 and older throughout the country. It is the nation's most comprehensive look at drug and alcohol use.
Last week, Attorney General Eric Holder announced that the Justice Department would not challenge states who have legalized use of small amounts of marijuana or medical marijuana if the states have strict measures to keep the drugs away from minors and have taken steps to regulate the drugs.
Two states, Washington and Colorado, have legalized marijuana, and 20 states have approved marijuana for medical use.
Until Attorney GenHolder's announcement Thursday, marijuana users in those states could face federal prosecution even if they adhered to state laws and local regulations.
Nearly 24 million Americans, about 9.2% of the population, use illicit drugs, the survey found. Illicit drugs include marijuana, cocaine, heroin, hallucinogens, inhalants and the non-medical use of painkillers, tranquilizers and stimulants. Marijuana is the most commonly used illicit drug.
While the abuse of prescription drugs, particularly opioids such as oxycodone, are stable or dropping, heroin use is on the rise, the survey found.
In 2012, 669,000 people reported using heroin, up from 620,000 people in 2011. The number of heroin users has jumped 80% since 2007, when 373,000 people reported using heroin.
"This finding show that while we have made progress in preventing some aspects of substance abuse, we must redouble our efforts to reduce and eliminate all forms of it throughout our nation," SAMHSA Administrator Pamela Hyde said.
"These statistics represent real people, families and communities dealing with the devastating consequences of abuse and addiction."