The ATP Tour's statistical leaders from 1991—the first year stats were collected—show how the game used to be dominated by the top servers. Over the years, that trend has shifted. In 1991, the top five servers were ranked in the top 10, but now in 2015, only three of the top five servers are ranked in the top 10.
The trend for return of serve statistics has changed in the opposite way. In 1991, no top 10 ranked players were near the top in return games won and only two of the top five returners had a singles ranking in the top 20. But by 2015, four of the top five in return games won were ranked in the top 10, with the lowest ranked player in the top 5 having a singles ranking of No. 13.
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