Dataset:   air_rpm.dat

Source: U.S. Bureau of Transportation Statistics

Description: Monthly U.S. Airline Available seat miles, revenue
passenger miles, and Unused seat miles, 1/79-1/04. (Billions?)

Variables/Columns:

Month 1-6   /* MMM-yy
Available seat miles   16-20
Revenue Passenger miles   26-30
Unused Seat Miles    36-40