Another way of putting it is that only 9 family names of more than two syllables have held the presidency. (subtracting Roosevelt and Harrison.)
Only 6 vice presidents have had names of longer than one syllable, and three of them were also presidents (Jefferson, Van Buren, T. Roosevelt), leaving Breckinridge (with Buchanan, no less!), Adlai Stevenson (with Cleveland) and Rockefeller -- and Rockefeller wasn’t even elected. Thus, only two men were elected to the vice presidency who had names the simple folk might have had trouble with.
So, out of 43 presidencies and 47 vice presidencies, only 14 men had names longer than two syllables. (15.5%)
I wonder what Vespucci would think of that.
Or McCain, Palin, Biden and -- Obama.