How many non-citizens participate in U.S. elections? More than 14 percent of non-citizens in both the 2008 and 2010 samples indicated that they were registered to vote. Furthermore, some of these non-citizens voted. Our best guess, based upon extrapolations from the portion of the sample with a verified vote, is that 6.4 percent of non-citizens voted in 2008 and 2.2 percent of non-citizens voted in 2010.
http://www.washingtonpost.com/blogs/...mber-election/

Not that it makes a difference to those who have decided that the integrity of our election system is not a big deal, but for the rest of us, more information on how votes cast by people not legally allowed to vote disenfranchise the rest of us (and, for the most part support Democrats).