In a $4.8 trillion punctuation point to a trend it has been highlighting for several years, Boeing says airlines are increasingly focused on the middle of the market.

The numbers come from the latest edition of its Current Market Outlook, Boeing’s 20-year forecast, which predicts that 35,000 aircraft will be purchased through 2032, an increase of 1,000 aircraft over last year’s $4.5 trillion prediction.

Between them, Boeing and Airbus are already 27% of the way to fulfilling this sales prediction because their combined backlogs are more than 9,500 aircraft.

Of the 41,000 aircraft Boeing expects to be in service in 2032, 59% will be bought to meet growth requirements and 41% will be replacements. Only 10% will be retained from current fleets.

Last year, 4 billion passengers travelled globally; by the end of its forecast, Boeing says that figure will climb to 9 billion.

The heart of the market is in its middle. Single-aisle transports, which Boeing defines as 90-230 seats, will account for 24,670 orders valued at $2.3 trillion. The middle extends to widebodies, with small widebodies seating 200-300 passengers accounting for 4,530 orders valued at $1.1 trillion, and medium widebodies seating 300-400 expected to sell 3,300 aircraft also worth $1.1 trillion.

Although the number of widebodies sold is only a third as many as single-aisles, their market value is nearly as much and, correspondingly, their profit margins are much higher.

In Boeing’s prediction, regional jets—those seating 90 or fewer passengers—will only generate 2,020 orders worth $80 billion, about the same as last year’s prediction.

Boeing Commercial Airplanes’ (BCA’s) Vice President-Marketing Randy Tinseth says that even the smaller seating single-aisles—the 90-150 crowd—will find sales hard to come by as carriers follow the long-term trend to higher capacity models. Both Boeing and Airbus are seeing weak response for the smallest of their 737 MAX and A320NEO single-aisle offerings. But their larger models are selling briskly.

Slow sales for Bombardier’s CSeries, the most serious new entrant in the 110-150-seat market, bears this out, Tinseth says. For its part, Bombardier says it is “guardedly optimistic” that more orders will be announced next week at the Paris air show as the company awaits the new family’s first test flight in late June.

Rising airline profitability is evidence that “our customers have been managing their fleets very, very well,” Tinseth says. Aside from the winter months when demand is traditionally weak, global load factors were comfortably in the 80-85% range in 2012. At its recent annual meeting, the International Air Transport Association confirmed that average load factors are growing and are now better than 80%. Last year they averaged 78%.

Not all sectors are performing so well. “We’ve been concerned about the growth rate for cargo aircraft for a long time,” Tinseth says. At 5%, this year’s forecast is slightly less optimistic than last year’s, which was for 5.1% annual growth. The current expectation is that 850 freighters will be ordered over the next two decades, 75% of them as big as a 777F or larger.

There is no demand for new smaller freighters although there will be a market for 767 converted freighters. The fact that 747-400s are being parked for lack of demand is not an indication that the fundamentals of air freight have changed, only that markets are slow, notes Tinseth.

As usual, Boeing factors in global GDP data in arriving at its expectations. Average annual GDP growth is set at 3.2%, the same as last year. But the annual average growth rate for passengers is much higher and up a full point from last year at 5%. “The reason why air travel grows faster than GDP is because it’s a bigger bargain,” says Mike Bair, BCA’s vice president of marketing and business development.