The games of the tournament follow the rules of the International Ice Hockey Federation (IIHF), which differ slightly from the rules used in the NHL. In the men's tournament, Canada was the most successful team of the first three decades, winning six of seven gold medals from 1924 to 1952. Czechoslovakia, Sweden and the United States were also competitive during this period and won multiple medals. Between 1920 and 1968, the Olympic hockey tournament was also counted as the Ice Hockey World Championship for that year. The Soviet Union first participated in 1956 and overtook Canada as the dominant international team, winning seven of the nine tournaments in which they participated. The United States won gold medals in 1960 and in 1980, which included their "Miracle on Ice" upset of the Soviet Union. Canada went 50 years without a gold medal, before winning one in 2002, and following it with back-to-back wins in 2010 and 2014. Other nations to win gold include Great Britain in 1936, the Unified Team in 1992, Sweden in 1994 and 2006 and the Czech Republic in 1998. Other medal-winning nations include Switzerland, Germany, Finland and Russia.