LOS ANGELES (CBSLA.com) — While cocaine use reportedly dropped heavily across the country between 2006 and 2010, the amount of marijuana use increased dramatically, according to a study released Monday by Santa Monica-based RAND Corp.

Marijuana consumed by Americans increased by over 30 percent from 2006 to 2010, while cocaine usage was cut by about half, according to the think tank’s researchers, who probed illegal drug use nationally between the years of 2000 and 2010.

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Heroin use, meanwhile, remained relatively steady throughout the decade, according to RAND.

Methamphetamine was another illegal drug whose consumption saw a dramatic increase during the first half the decade before declining. Researchers did not have enough information to state a credible estimate of the use of the drug from 2008 to 2010.

The findings were made public from a report compiled for the White House Office of National Drug Control Policy by researchers affiliated with the RAND Drug Policy Research Center.

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“Having credible estimates of the number of heavy drug users and how much they spend is critical for evaluating policies, making decisions about treatment funding and understanding the drug revenues going to criminal organizations,” said Beau Kilmer, who is the lead author of the study.

Kilmer is also the co-director of the RAND Drug Policy Research Center.

“This work synthesizes information from many sources to present best estimates to date for illicit drug consumption and spending in the United States,” Kilmer said.

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