From the 1920 Olympics until the 1976 World Championships, only athletes designated as "amateur" were allowed to compete in the tournament.Because of this, players from the National Hockey League and its senior minor-league teams were not allowed to compete, while the Soviet Union was allowed to use permanent full-time players who were positioned as regular workers of an aircraft industry or tractor industry employer that sponsored what would be presented as an after-hours amateur social sports society team for their workers.In 1970, after an agreement to allow just a small number of its professionals to participate was rescinded by the IIHF, Canada withdrew from the tournament.[2] Starting in 1977, professional athletes were allowed to compete in the tournament and Canada re-entered, using some NHL players from those teams that were not good enough to reach the Stanley Cup playoffs.[8][9][10][11] The table shows players who have won at least 11 medals in total at the World Championships.