A new report by the National Highway Transportation Safety Administration in the U.S. says that 18 per cent of all drivers killed in car accidents in 2009 tested positive for drugs that might impair driving. That’s up from the 13 per cent of dead drivers who tested positive in 2005. “Today’s report provides a warning signal that too many Americans are driving after having taken drugs, not realizing the potential for putting themselves and others on the highway at risk,” NHTSA Administrator David Strickland told the Washington Post. The drugs included in the study range from illegal hallucinogens to legal pain-killers that cause drowsiness. The percentage of drivers tested for drugs in fatal crashes was also up, from 56 per cent in 2005 to 63 per cent in 2009.