Washington State experiences 40% increase in share of total driving cases testing positive for recent marijuana use since drug was legalized

Data adapted from the Washington State Patrol and Washington State Toxicologist shows that in 2013, the percentage of total driving cases where the driver tested positive for Carboxy-THC, indicating recent use, rose 40%. From 2011-2012, there was only a 0.70% increase, and 2010-2011 witnessed only a 0.71% increase.
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