The airline industry may be struggling, but Boeing ( BA) says the future for its jets is bright. In its 2004 Current Market Outlook Survey, released at the Farnborough Air Show in the U.K., the global aerospace giant forecast that there will be a $5.4 trillion market for new commercial aircraft and aviation services over the next 20 years. By 2023, the company said, the number of aircraft in service will double, with world air travel increasing by 5.2% annually. "The long-term market outlook remains positive," said Randy Baseler, vice president of marketing at the company's commercial jet unit. "Even severe downturns such as we've experienced during the past few years do not change the fundamentals of economic growth and the need for people to travel." At the air show, Boeing also gave an update on the status of its fuel-efficient, medium-sized 7E7 Dreamliner, saying that all delivery slots for 2008 and 2009 were fully booked and that it was already 80% booked for 2010. Boeing said that, so far, four carriers have ordered 62 planes, with another two dozen ordering about 200 more. In reaction, shares of Boeing fell 8 cents, or 0.2%, to $48.59. Entering the month, Boeing shares were up 20% year to date as the carrier worked through an ethics scandal at the end of 2003. Over the next two decades, Boeing said that carriers will invest $2 trillion on 25,000 new jets, but the majority of that growth will not come from the massive planes flown by the struggling network carriers. Boeing said that 59% of the planes sold will be single-aisle jets, with 21% intermediate, twin-aisle jets and 17% smaller regional jets. Only 3% of the growth will come from 747s or larger planes. The remainder of the expected growth -- $3.4 trillion -- will come from commercial aviation support services, as Boeing maintains and refurbishes the planes it has already sold.