I'm looking up some wikipedia articles on popular vote results.
Wait... they don't amount to 100%?...
Not sure what pages you're looking at but remember there are 3rd party candidates and even write in candidates that we never see.
Every year MIckey Mouse gets a bunch of write in votes. In 2012 Willie Nelson got votes.
Might see these write in votes lead to a siphoning of the 100% total.