<Li> Mark McGwire - 8.13 </Li> <Li> Barry Bonds - 8.29 </Li> <P> Babe Ruth was the first batter to average fewer than nine at - bats per home run over a season, hitting his 54 home runs of the 1920 season in 457 at - bats; an average of 8.463 . Seventy - eight years later, Mark McGwire became the first batter to average fewer than eight AB / HR, hitting his 70 home runs of the 1998 season in 509 at - bats (an average of 7.2714). In 2001, Barry Bonds became the first batter to average fewer than seven AB / HR, setting the Major League record by hitting his 73 home runs of the 2001 season in 476 at - bats for an average of 6.5205 . </P> <P> Ruth, McGwire and Bonds are the only batters in history to average nine or fewer AB / HR over a season, having done so nine times: </P>

Who averaged the most home runs per season