Nearly 80 percent of all crashes involved driver inattention

100-Car Naturalistic Study - Virginia Tech Transportation Institute

"Nearly 80 percent of all crashes and 65 percent of all near-crashes involved driver inattention (due to distraction, fatigue, or just looking away) just prior to (i.e., within 3 seconds) the onset of the conflict."

http://ssl.csg.org/dockets/2011cycle/31B/31Bbills/100-Car_Fact-Sheet.pdf