I found this at about.com, last years attendance numbers:
#1 The Magic Kingdom at Walt Disney World, Lake Buena Vista, Fla., 14 million, flat.
#2 Disneyland, Anaheim, Calif., 12.7 million, flat.
#3 Epcot at Walt Disney World, Lake Buena Vista, Fla., 8.6 million, up 4 percent.
#4 Disney-MGM...