Who has been ranked 1 in tennis the longest?

Related questions

1. How much money did Coco Gauff earn at Wimbledon?
2. Who advanced at Wimbledon?
3. Who won Wimbledon men's 2019?
4. Who is the oldest Grand Slam tennis winner?
5. Is Serena or Venus Williams older?
6. Is Kiki Bertens married?
7. Who is ranked higher Venus or Serena Williams?
8. Who won today at Wimbledon?
9. Who is the oldest out of Serena and Venus Williams?
10. Is Cori Gauff a professional?

Tags

1. #spanning
2. #three
3. #federer
4. #weeks
5. #career
6. #world
7. #record
8. #ranking
9. #introduced
10. #number
11. #winner
12. #titles
13. #separate
14. #ranked
15. #total
16. #since
17. #holds
18. #periods
19. #system
20. #grand
21. #roger
22. #computerized