To estimate regular normal selling prices, KAYAK normally takes all charges for each and every month throughout the last calendar year for round-journey flights from London to Atlanta, gets rid of the top 0.one% to account for outliers, and then will take the median of all values for each month. https://www.diigo.com/item/note/aa9i2/807k?k=fb025331b686431f3de7413d6bcdd4fe