 Complete the following phrase:  The first official tournament was held in 1977, although the first three tournaments from 1974 to 1976 were held unofficially. The tournament has been dominated by the teams from Soviet UnionCISRussia and Canada, together accounting for 31 of the 45 overall gold medals awarded through 2021. The USSR won the first four official tournaments, while the Canadians put together five straight championships between 1993 and 1997, and another five straight from 2005 to 