Since the ATP computerized ranking was introduced in 1973, 100 players have spent at least one week inside the ATP Top 20. The all-time leader is Roger Federer with 1064 weeks, a margin 7% ahead of Novak Djokovic (991 weeks) and Rafael Nadal (927 weeks). 100 players have accumulated 52 or more weeks inside the Top 20, with an average of 390 weeks across all ranked players.