To estimate month-to-month typical charges, KAYAK requires all charges for each month during the last calendar year for flights from London Heathrow Airport to Austin, gets rid of the very best 0.1% to account for outliers, and then requires the median of all values for monthly. True flight was easy https://thejillist.com/story8604564/the-2-minute-rule-for-cheap-flights-to-baltimore