Note that this stat is based on 2008 exit polls. If Mitt Romney runs in the November election, it is likely this ratio will increase. Letters were read in Mormon wards this month encouraging political involvement.
Excerpts of "Mormon voters wary of too much public support for Romney" by Sandhya Somashekhar, Washington Post
--In 2008, Mormons made up about 11 percent of the Republican primary electorate, according to exit polls. Though they are not a large group nationally — about 2 percent of the U.S. population — they are overwhelmingly conservative and are more likely to vote than other groups.