To calculate every month average charges, KAYAK requires all selling prices for every month throughout the last 12 months for flights from London Heathrow Airport to Austin, eliminates the best 0.1% to account for outliers, after which you can requires the median of all values for on a monthly basis. https://bookmarkcitizen.com/story18529957/the-2-minute-rule-for-cheap-flights-to-baltimore