Simplify the following text for a Grade 10 native English-speaking person.
Original: Up to and including the 2011 Australian Grand Prix , 840 World Championship Grands Prix have been held , including the Indianapolis 500 races which were a part of the World Championships from 1950 until 1960 .
Simplified: At the end of the 2008 season , 803 World Championship Grands Prix will have been held including the Indy 500 which was a part of the World Championship from 1950 until 1960 .