In that case, 51% of American Christians are literalists, since that's the percentage who believe in intelligent design.
The two groups (evolution vs. intelligent design) are not mutually exclusive. I fully believe in the big bang and the process of evolution, but why couldn't a higher power have a hand in that? Call it 'divine evolution'.
Even if your theory is that without a God, we wouldn't have evolved into humans, you're still conflating evolution with something else that happens to have interacted with it to reach a certain end. People who believe that life would not have arisen on earth if the planet orbited the sun 5% more slowly don't claim that this is an entirely separate belief from evolution; people who believe that God (rather than orbital speed) was a deciding factor don't need a new theory, either.
People tend to think it's creationism, when in fact they are diametrically opposite methodologies. Creationism is entirely deductive, whereas intelligent design is inductive. A good hint here is that ID is hated by creationists as well as Darwinists.
Creationism starts with the theory that a particular interpretation of the Bible is correct, and attempts to find evidence for the theory.
Intelligent design, on the other hand, is the conjecture that intelligent/intentional causation is empirically distinguishable from physical causation. Therefore, it attempts to develop falsifiable hypotheses, such as Dembski's explanatory filter.
Additionally, it is common descent ambivalent. Common descent, old earth, etc. may or may not be true for all it cares. However, ID contradicts Darwinism, since Darwinism implies intelligence and intent are produced only by physical laws, thus indistinguishable from physical causation.
I do not want to be a troll. I only want to help correct a very common and very annoying misunderstanding. If someone wants to discuss it more offline, I'd be more than happy to do so.
http://www.cbsnews.com/stories/2005/10/22/opinion/polls/main...
The trend between the two polls shown is encouraging though. In one year 4% of the population shifted in the right direction.