The short version?
It was a hard hit, no doubt. 2002 seems to be where most of the numbers bottom out, so I'll use that. Resort as a whole was off -13% from 2000. Epcot took the hardest hit, dropping 22%. DAK/DHS were around 10% drop and MK dropped 9%.
Everything has rebounded and grew and grew.... The resort as a whole is up 37% since 2002. MK/EP up 38% since then, DAK up 42%. Studios lagging at 29% growth since then.
Looking at 2005 and forward, (past 10 years) Everything is growing at about the same rate. Resort as a whole is up 24%, MK/DHS 23%, DAK up 31% and Epcot at 19%. Resort as a whole is up 20% since 2005. MK is up 20% with Studios. Epcot a tad behind at 16% and DAK growing nicely at 27% over the past 10 years.
In the near term, MK is growing at a rate double of all the other parks. Since 2011, MK is up 13% while the other 3 parks are hovering around 6%. Resort as a whole is up 8.5%
I'll dive more into this years numbers after the 4th of july.
(Sources = Amusement Business, TEA)
EDIT= Damn Spreadsheet.