An Order of Merit was introduced for the 1975/1976 season, which saw Ray Reardon ranked in the top position. This system was only in place for a season before being replaced by the world rankings, which saw successive periods of dominance for the first 22 seasons by Ray Reardon (1976/1977–1982/1983), Steve Davis (1983/1984–1989/1990) and Stephen Hendry (1990/1991–1997/1998), interrupted only by the 1981/1982 season when Cliff Thorburn held the position. The following period (1998/1999–2009/2010) was shared by Ronnie O'Sullivan (five seasons), John Higgins (three seasons) and Mark Williams (three seasons), while Hendry regained the position for the 2006/2007 season. In the first 34 years of the world rankings, only seven players held the number-one position.