To Work out every month ordinary prices, KAYAK requires all charges for each and every month over the past 12 months for spherical-vacation flights from London to Atlanta, eliminates the highest 0.1% to account for outliers, and then will take the median of all values for each and every month. https://www.diigo.com/item/note/aa9i2/807k?k=fb025331b686431f3de7413d6bcdd4fe