I'd say that number is probably higher - I know a number of people who believe evolution happens but think that humanity didn't evolve from monkeys. Because we are special, or something. I generally don't query further.
It is higher among the educated, and lower among those with a HS degree or less:
http://sas-origin.onstreammedia.com/origin/gallupinc/GallupS...
(Obligatory reminder that schooling is no assurance of education.)
Yes, and (snicker, snicker) we therefore evolved from a creature that was "lower" than a monkey. :)