Boeing projects a demand for 36,770 new airplanes over the next 20 years, an increase of 4.2 percent from last year’s forecast.

The company released its annual Current Market Outlook Thursday in London, estimating the total value of those new airplanes at $5.2 trillion.

“This market is strong and resilient,” said Randy Tinseth, vice president of Marketing, Boeing Commercial Airplanes, in a company news release. “With new and more efficient airplanes entering service, the growth in air travel is being driven by customers who want to fly where they want, when they want.”

Fueling this year’s forecast is the single-aisle market, which is projected to be the fastest growing and most dynamic segment due to the continued emergence of low-cost carriers, according to Boeing. 25,680 new airplanes will be needed in this segment, making up 70 percent of the total units in the forecast.

The dollar value of the single-aisle planes is placed at about $2.6 trillion.

“Based on the overwhelming amount of orders and deliveries, we see the heart of the single-aisle market in the 160-seat range,” said Tinseth. “There’s no question the market is converging to this size, where network flexibility and cost efficiency meet. The Next-Generation 737-800 and new 737 MAX 8 offer our customers the most revenue potential in this mid-sized space.”

Boeing forecasts that 8,600 new airplanes will be needed in the twin-aisle segment, led by small widebody airplanes in the 200 to 300 seat range such as the 787-8 and 787-9 Dreamliner. This year’s forecast reflects a continued shift in demand from very large airplanes to efficient new twin-engine products such as the 787-10 and new 777X.

“With the most comprehensive widebody lineup in the industry, we’re confident that we will meet our customers’ needs now and in the future,” Tinseth added.