an interesting quote from the link I provided:
CIRCLE’s review of exit poll data indicates that the number of young people, and likewise the percentage of eligible voters ages 18 to 29, has increased since the 1990s. In 1996, 14.5 million young people voted in the presidential election, representing 37 percent of total eligible voters ages 18 to 29. In the 2000 presidential election, voting among 18 to 29 year olds increased to 16.2 million (41 percent of eligible voters); in 2004, to 19.4 million (48 percent of eligible voters); and in 2008, to 22.8 million (52 percent of eligible voters). Early exit poll results indicate that between 22 and 23 million people ages 18 to 29 voted in the 2012 presidential election, making up 19 percent of all voters. Exit poll data indicates that among voters of that age range, President Obama received 60 percent of the votes and Governor Romney received 37 percent.