Please answer a question about the following article about Oklahoma City:

Oklahoma City is served by two primary airports, Will Rogers World Airport and the much smaller Wiley Post Airport (incidentally, the two honorees died in the same plane crash in Alaska) Will Rogers World Airport is the state's busiest commercial airport, with over 3.6 million passengers annually. Tinker Air Force Base, in southeast Oklahoma City, is the largest military air depot in the nation; a major maintenance and deployment facility for the Navy and the Air Force, and the second largest military institution in the state (after Fort Sill in Lawton).

Which airport is the busiest?
Will Rogers World Airport