Boeing Co boosted its 20-year forecast for aircraft demand by 3.5 percent, predicting two out of every five new jets will feed Asia’s booming travel market. The U.S. planemaker expects airlines and freight firms to take delivery of 38,050 jets worth $5.6 trillion by 2034, compared with 36,770 it predicted last year. Boeing’s forecast comes ahead of the industry’s annual showcase, the June 15-21 Paris Airshow, where jetmakers will be drumming up business and gauging the reliability of suppliers to keep pace with record jet production. Boeing shaved its prediction for annual airline traffic growth to 4.9 percent from 5.0 percent for the period, including a sharp downward revision for Russia, hit by falling oil prices. Randy Tinseth, Boeing vice president for marketing, said in a conference call that the company was in no rush to develop a replacement for its 757, an aircraft between the largest single-aisle planes and the smallest double-aisle jets. Airline officials at an industry gathering this week in Miami said they were increasingly interested in Airbus’ A321neo to fill that so-called “middle of the market” gap “We certainly have time to make a decision and we’ll take that time,” Tinseth said. Boeing has said the jet would be available around 2030. Boeing’s stock rose 1 percent to $143.02 in midday trading in New York. Single-aisle aircraft such as Boeing’s 737 and Airbus’ A320 will account for $2.7 trillion in the next 20 years, or 26,730 jets, Boeing said. It revised up its forecasts for twin-engine jets like the Boeing 787 and Airbus A350. But it again lowered its view of demand for four-engine jumbos: the Airbus A380 and Boeing 747. The companies disagree about demand for jets with seating for over 400 people. Boeing predicted deliveries of 540 of these planes in the next 20 years, down from 620 a year ago, leaving little room for the A380 which is struggling for orders. In its last forecast issued in 2014, Airbus predicted 1,500 deliveries of the A380 and 747 over 20 years. Boeing maintained its long-range forecast for average annual cargo traffic growth at 4.7 percent, but said the market was strengthening and that this trend would continue.