There are many companies who keep track of statistics for flights and airports. Some of it is online and paying users often get more coverage in terms of historical data or more fine-grain details.
You can check FlightStats which have tons of statistics. This page lists Airlines, Airport Arrival and Airport Departure delays.
Another slightly harder website to read is the Bureau of Transport Statistics where you can query statistics for different airlines, airports and time windows. Try this page for example. Pluging in ATL (Hartsfield–Jackson Atlanta International Airport) for the last three months today shows that there are 4% carrier delays and 5.4% late arrivals there.