Can you give more detail as to what you require?
A starting point would be to google airport statistics.
Various airports provide statistics,some more detailed than others, e,g:
http://www.panynj.gov/airports/pdf-traffic/ATR2011.pdf
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Orlando International Airport (MCO) - Traffic Statistics etc
The US Bureau of Transportation Statistics has a lot of data:
RITA | Bureau of Transportation Statistics (BTS)
For international routes:
Contents
Lots of free stats on the web if you look but unfortunately detailed stats (and info like yield which you really need if you want to plan new routes) can cost money.