Boeing has been the premier manufacturer of commercial jetliners for more than 40 years. With the merger of Boeing and McDonnell Douglas in 1997, Boeing's leadership in commercial jets, joined with the lineage of Douglas airplanes, gives the combined company a 70-year heritage of leadership in commercial aviation. Today, the main commercial products are the 737, 747, 767 and 777 families of airplanes and the Boeing Business Jet. New product development efforts are focused on the Boeing 787 Dreamliner, and the 747-8. The company has nearly 12,000 commercial jetliners in service worldwide, which is roughly 75 percent of the world fleet. Through Boeing Commercial Aviation Services, the company provides unsurpassed, around-the-clock technical support to help operators maintain their airplanes in peak operating condition. Commercial Aviation Services offers a full range of world-class engineering, modification, logistics and information services to its global customer base, which includes the world's passenger and cargo airlines, as well as maintenance, repair and overhaul facilities. Boeing also trains maintenance and flight crews in the 100-seat-and-above airliner market through Boeing Training & Flight Services, the world's largest and most comprehensive provider of airline training.