Passage: Introduced in 1957, the Sportster family were conceived as racing motorcycles, and were popular on dirt and flat-track race courses through the 1960s and 1970s. Smaller and lighter than the other Harley models, contemporary Sportsters make use of 883 cc or 1,200 cc Evolution engines and, though often modified, remain similar in appearance to their racing ancestors.Up until the 2003 model year, the engine on the Sportster was rigidly mounted to the frame. The 2004 Sportster received a new frame accommodating a rubber-mounted engine. This made the bike heavier and reduced the available lean angle, while it reduced the amount of vibration transmitted to the frame and the rider, providing a smoother ride for rider and passenger.In the 2007 model year, Harley-Davidson celebrated the 50th anniversary of the Sportster and produced a limited edition called the XL50, of which only 2000 were made for sale worldwide. Each motorcycle was individually numbered and came in one of two colors, Mirage Pearl Orange or Vivid Black. Also in 2007, electronic fuel injection was introduced to the Sportster family, and the Nightster model was introduced in mid-year. In 2009, Harley-Davidson added the Iron 883 to the Sportster line, as part of the Dark Custom series.

Question: When were the Sportsters added?
1957