What do Amanda Bynes, John Liu, teenagers, Woody Harrelson, Funyuns aficionados, Morgan Freeman, and Rob Ford all have in common? An abiding love for the devil's weed, of course! According to a new study, they aren't the only ones: marijuana is the most popular, least deadly illegal drug in the whole world. Which perhaps explains the fact that Taco Bell Doritos Locos has singlehandedly revived the economy.

The study, published by the Institute for Health Metrics and Evaluation at the University of Washington, found that painkillers such as Vicodin, Oxycontin and codeine kill the most people. Of the estimated 78,000 deaths in 2010 because of illegal drug use, more than half were because of painkiller addictions. Researchers found that for all the drugs studied (including cocaine and amphetamine, but not hallucinogens and Ecstasy), men in their 20's had the highest rates of abuse, and the worst-hit countries were Australia, Britain, Russia and the U.S.

"Even if it is not very solid data, we can say definitely that there are drug problems in most parts of the world," said Theo Vos, one of the authors of the study. He added that the study points to the need for reform on drug laws: countries with the harshest penalties against drugs had worse death rates for addicts compared to countries who relied on other policies (exchange programs, methadone clinics) to wean people off drugs.

"A decriminalized drug policy could potentially transform the public health approach to drug use," said Vikram Patel, of the Centre for Global Mental Health at the London School of Hygiene and Tropical Medicine. "The enormous savings in the criminal justice system could be used to fund addiction treatment programs." But when you have a mayor who thinks medical marijuana is a hoax and drug dealers can't possibly find a new line of work, change doesn't come easily.