In 1951, thirteen nations took part and were split into two groups. The top seven teams (Pool A) played for the World Championship. The other six (Pool B) played for ranking purposes. Generally eight teams played in the top-level Championship, although the number varied over the years, going as low as three (in 1953) and as high as twelve (in 1959). The same format was used until 1992. The format was criticized because often the gold medal winner was decided before the final game was played, such as at the 1988 Winter Olympics.