The WTA Rankings are the ratings defined by the Women's Tennis Association, introduced in November 1975.
WTA Rankings Wikipedia
The WTA rankings are based on a rolling 52-week, cumulative system. A player's ranking is determined by her results at a maximum of 16 tournaments for singles and 11 for doubles and points are awarded based on how far a player advances in a tournament. The basis for calculating a player's ranking are those tournaments that yield the highest ranking points during the rolling 52-week period with the condition that they must include points from the Grand Slams, Premier Mandatory tournaments and the WTA Finals. In addition, for Top 20 players, their best two results at Premier 5 tournaments will also count. The WTA also distributes ranking points, for singles players only, who compete at the Summer Olympics. Points earned at the Summer Olympics will only apply to a player's overall ranking during that calendar year.
The points distribution for tournaments in 2015 is shown below. Points earned in 2013 were a little different in some cases and retain their value until they expire after 52 weeks.
"+H" indicates that Hospitality is provided.
The following is a chronological list of players who have achieved the number one position in singles since the WTA began producing computerized rankings on November 3, 1975 (active players in green):
Last update: 20 March 2017
The year-end number one player is the player at the head of the WTA rankings following the completion of the final tournament of the calendar year.