2008 VOTE
Obama 83% 9% 8%
McCain 2% 94% 4%
So, 9% of those that voted for zero are voting for Romney, and 8% are undecided. That means that 17% have gotten or are getting a clue.
As for the 2% that voted for McCain that are voting for zero - anyone ever met one of these people?
Unsurprising fact: at least 2% of Democrats are flat-out liars.