In 2012 there were 30,800 fatal motor vehicle crashes.
In 2012, 10,322 involved alcohol. (31%)
In 2012 there were 112 million self reported episodes of alcohol-impaired driving.
The population of the US is 316 million.
I think the statistics speak for themselves, drunk driving does not significantly increase the chance for a fatal accident. We just happen to be a nation of drunks.