"The number of hours that players
were exposed to risk during competition was
calculated for each club by assuming that 11
players from the club were on the pitch at all
times during each match and that each match
lasted for 100 minutes (45 minutes standard
play plus five minutes extra time each half)."
So 1000/ (11players * (100/60))= 54.54 games or 1 injury every 1.97 games