Low-cost carriers and regional airlines have revolutionized the airline business with the introduction of innovative low-fare business models. Notwithstanding the fact that airlines such as Easyjet and Ryanair have steadily eaten into the market share of major transportation companies, Georgia-based Delta Air Lines remained the leading airline in terms of passenger miles flown in 2012, followed by United/Continental, Southwest, American Airways and Lufthansa. Aviation demand is set to be fuelled by the rising affluence of the middle classes in emerging markets. Consequently, the air traffic industry is forecast to grow most significantly in Latin America, the Middle East and the Asia-Pacific region. In 2012, the airports in Atlanta (IATA: ATL), Beijing (IATA: PEK) and London (IATA: LHR) were ranked as the three major airports for passenger traffic.