How Many Americans are Young Earth Creationists?

As near as I can tell (by reading the StraightDope website), Gallup polling from 1982 to 2006 puts 44% to 47% of Americans as Young Earth Creationists, the number that choose this answer to a question about human origins:

"God created human beings pretty much in their present form at one time within the last 10,000 years or so."

It's likely that this question inflates the number of people who would, in an essay, let's say (I'll make the joke about whether half of Americans know what one is or could write the essay, please, and we'll move on), describe human origins in this way. I'm not a pollster, but I think that is a leading question, and inflates the Young Earth respondents. Nevertheless, that's still a higher figure than I would have expected. I'd have thought that almost nobody outside of fundamentalist Christian denominations would answer that question that way, and that a good percentage of fundamentalists would answer it differently. I expected a figure of about ten percent, inflated by leading polling to perhaps twenty percent. It looks like I was wrong.