There were unofficial lists in 1964, 1969, 1970 and January 1971, as the
Elo rating system was first introduced. From 1971 to 1980, there was one main rating list published each year (for a total of 10), initially published in July from 1971 to 1973, then once in May (1974), before switching to annual publication in January from 1975 to 1980 (in this period, some supplements and amendments were also published). From 1981 to July 2000, two lists per year were published, in January and July (for a total of 39 lists). In July 2000, the publication schedule was increased to four times a year (January, April, July, October) operating from July 2000 to July 2009 (for a total of 36 lists). In July 2009, the publication schedule was increased again, to six times a year (January, March, May, July, September, November) operating from July 2009 to July 2012 (for a total of 18 lists). In July 2012 the publication schedule was increased again to the current monthly schedule. Publication of the rating lists in the 1970s and 1980s was in
Chess Informant and other chess publications. The number of games played by individuals during the rating period was added to the lists from July 1985 onwards. Player ID numbers were used from January 1990. From January 1999, the practice of rounding to the nearest five Elo points was discontinued, and ratings were then rounded to the nearest Elo point for publication. From July 2000 onwards, the ratings are available from the FIDE website. Although Spassky was World Champion during the inception of the FIDE rankings in 1971, he never became the number-one rated player in the world; since July 1971 he, Vladimir Kramnik,
Ding Liren, and
Gukesh Dommaraju (the current Champion) are the only undisputed World Champions to never become ranked world number one during their tenure as champions (Kramnik has been ranked number one, but never while he was champion. Spassky and Ding have their peak ranking as World No. 2; Gukesh as World No. 3.) == List of world number ones ==