Who knows statistics about superheroes?

Specifically, I'm trying to find this statistic I read somewhere that more people recognize this one superhero (I seem to remember that it was Batman, but it could be Superman or even Spiderman) than some extremely historically/culturally important icon. This sounds vague, I'm aware; it's one of those facts that a book or a site mentions to demonstrate how dumb and out of touch Americans are. It's something like "More American children recognize Batman than, say, George Washington", or "80% of American children recognize Batman, but only 40% were able to correctly identify George Washington". Something like that. I'm looking for this particular fact for a paper I'm writing on superheroes in American pop culture. If anyone knows what I'm talking about, please let me know what the correct wording of this stat is, and if possible, where you got it from. The internet has proved rather unhelpful for me so far.