To work out every day average charges, KAYAK will take all charges for day after day before departure during the last calendar year for flights from London Heathrow Airport to Austin, eliminates the best 0.1% to account for outliers, then usually takes the average of each of the values for https://www.evernote.com/shard/s668/sh/54a4e382-4d79-3bb7-2039-2763b9ae4779/6rYxR7G4r96SUKueOQxa0CZyQSOvIsWuXy7GRYr8rbLDbg6wb9BFEQnXEQ