And while I understand the table-turning fascination that this question has for some people, I think I'll echo Lily: "I'm not convinced this is territory into which Bush supporters should wander." And I think she's also right to add "I'm not sure any of it says much about their fitness for the presidency."
Our smartest (modern) presidents, after all, were probably Herbert Hoover and Jimmy Carter.
UPDATE: David Levy emails:
Haven't you forgotten Richard Nixon? One of my teachers, George J Stigler, thought he was off the scale. And George was a very good judge of such things.
From which one concludes many things ...
As Jurgen learned in the end, cleverness is not on top, and never has been.