Dassault Falcon 50 and derivatives with three; and the Cirrus Vision SF50 with one, a configuration also used in several similar very light jet design concepts. Most business jets use podded engines mounted on the rear fuselage with a cruciform tail or T-tail to reduce interference drag and increase exhaust clearance. Practical limits on the ground clearance of these smaller aircraft have prompted designers to avoid the common jetliner configuration of a low wing with underslung podded engines. The sole business jet to use this layout, the early McDonnell 119, was rejected by the USAF due to foreign object damage concerns, leading to the failure of the program. The recent HondaJet uses wing-mounted engines but mitigates this problem with its unique over-the-wing engine pods. As with jetliners, swept wings are often used to increase cruise speed, but straight wings are also commonplace; notably, Cessna deliberately prioritized docile low-speed handling in choosing straight wings for many models in its popular Citation family, envisioning that owners transitioning from slower piston engined or turboprop aircraft would want to maintain the ability to use relatively short runways, and that lower approach speeds would ease single-pilot operations, particularly by relatively inexperienced owner-pilots. Rolls-Royce plc powers over 3,000 business jets, 42% of the fleet: all the Gulfstreams and Bombardier Globals, the Cessna Citation X and Embraer Legacy 600, early Hawkers, and many small jets with the Williams-Rolls FJ44. Market Fleet About 70% of the fleet was in North America at the end of 2011, the European market is the next largest, with growing activity in the Middle East, Asia, and Central America. On 1 April 2017, there were 22,368 business jets in the worldwide fleet, of which 11.2% were for sale. By October 2018, the entire private jet fleet was dominated by Textron (Beechcraft, Cessna and Hawker branded aircraft) with 43.9%, then Bombardier with 22.4%, Gulfstream with 13.0%, Dassault with 9.6% and Embraer with 5.8%, mostly in North America (64.6%), followed by Europe (13.0%) South America (12.1%) and Asia-Pacific (5.9%). As on March 31, 2019, there are 22,125 business jets in the worldwide fleet and top 20 country markets account for 89% of this total fleet. Market shares In 2015 the total airplane billing amounted to US$21.9 billion, and 718 business jets were delivered to customers across the globe: 199 (%) by Bombardier Aerospace, 166 (%) by Textron Aviation, 154 (%) by Gulfstream Aerospace, 120 (%)