To determine every day average selling prices, KAYAK normally takes all costs for on a daily basis before departure over the past year for flights from London Heathrow Airport to Austin, removes the best 0.1% to account for outliers, then takes the average of the many values for every month. https://businessclassflightstosydney.wordpress.com/2024/07/23/some-insights-about-popular-holiday-packages/