The numbers cite each carrier's cancellation and mishandled baggage rate for July 2007, the most recent month for which data is available, plus average on-time performance from July 2006 to July 2007.
Since then, the airline has taken serious measures to improve its efficiency, including rebuilding its luggage system at its Atlanta hub to cut down on lost baggage, and analysing historical cancellation data to adjust the availability of spare aircraft in different hubs in order to keep flights moving.