The Current Market Outlook is our long-term forecast of air traffic volumes and airplane demand. The forecast has several important practical applications. It helps shape our product strategy and provides guidance for our long-term business planning. We have shared the forecast with the public since 1964 to help airlines, suppliers, and the financial community make informed decisions.
Each year we start new, so we can factor the effects of current business conditions and developments into our analysis of the long-term drivers of air travel. The forecast details demand for passenger and freighter airplanes, both for fleet growth and for replacement of airplanes that retire during the forecast period. We also project the demand for conversion of passenger airplanes to freighters.
The remarkable resilience of air travel is amply documented in nearly 50 years of published editions of the Boeing Current Market Outlook.
Commercial aviation has weathered many downturns in the past. Yet recovery has followed quickly as the industry reliably returned to its long-term growth rate of approximately 5 percent per year. Despite uncertainties, 2011 passenger traffic rose 6 percent above 2010 levels. We expect this trend to continue over the next 20 years, with world passenger traffic growing 5 percent annually. Air cargo traffic has been moderating after a high period in 2010. Air cargo contracted by 2.4 percent in 2011. Expansion of emerging-market economies will, however, foster a growing need for fast, efficient transport of goods. We estimate that air cargo will grow 5.2 percent annually through 2031.
We forecast a long-term demand for 34,000 new airplanes, valued at $4.5 trillion. These new airplanes will replace older, less efficient airplanes, benefiting airlines and passengers and stimulating growth in emerging markets and innovation in airline business models. Approximately 23,240 airplanes (68 percent of new deliveries) will be single-aisle airplanes, reflecting growth in emerging markets, such as China, and the continued expansion of low-cost carriers throughout the world. The twin-aisle segment will also increase, from a 19 percent share of today's fleet to a 23 percent share in 2031. The 7,950 new twin-aisle airplanes will allow airlines to continue expansion into more international markets.