Complex sentence: In the 1990s, NBC broadcast a doubleheader each year on Christmas Day and this has continued after ABC took over in, except that in 2004 and 2006, ABC broadcast only one game.
Split into simpler sentences: In the 1990s, NBC broadcast a doubleheader each year on Christmas Day and this has continued after ABC took over in. However, in 2004 and 2006, ABC broadcast only one game.