From the Denver Post:

"In Colorado, THC or some other form of marijuana showed up in 26 of the 312 drivers killed that year."

That's 8.3% of drivers. I bet over 10% of CO residents would have detectable THC or metabolites in their system at any given time, if so that means you are less likely to die in a car accident compared to the general population. That's why we call 'em "safety breaks" when snowboarding and mt. biking.