The Boeing family of 737 jetliners is helping to make low-fare airlines the fastest growing market in Europe. Today, low-fare airlines account for only 4 percent of European travel, but they are showing a phenomenal passenger growth rate of 30 percent a year. Nine out of 10 airplanes operated by European low-fare carriers are 737s. The keys to the 737's success with these airlines are the airplane's low operating costs and superior reliability and maintainability.