No. 1 in the end of seasons, by decades:
70s: (since ’73): Năstase – Connors – Connors – Connors – Connors (Vilas) – Connors – Borg
80s: Borg – McEnroe – McEnroe – McEnroe – McEnroe – Lendl – Lendl – Lendl – Wilander – Lendl
90s: Edberg – Edberg – Courier – Sampras – Sampras – Sampras – Sampras – Sampras – Sampras – Agassi
00s: Kuerten – Hewitt – Hewitt – Roddick – Federer – Federer – Federer – Federer – Nadal – Federer
10s: Nadal – Đoković – Đoković – Nadal – Đoković – Đoković – Murray – Nadal – Đoković – Nadal
20s: Đoković – Đoković – Alcaraz – Đoković – Sinner –
The Top 20 ranking at the end of each season in the years 2019-1973. Top ’20s are divided into decades with statistical summaries, under every year additional notes (biggest national representation, number of left-handers, number of players with one-handed backhand, number of serve-and-volleyers). It must be said that S&V exposition is a bit tricky because there were players, who either changed tactics over years or were adapting different tactics within a year in regard to a surface they played on, therefore those numbers have to be regarded with a pinch of salt 😉
# In the picture Jimmy Connors – the legend of the 70s & 80s, the man who finished the most years in the Top 20 – seventeen (16 consecutive years in the Top 10)! Federer overcame him in 2018…
RH – right-handed; LH – left-handed
DH – double-handed backhand; DBHS – double-handed from both sides; / – one-handed backhand
Blue – youngest player(s); Red – oldest player(s)
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Unofficial Top 10 in years 1972-1968
1972
1 Smith, Stan (USA)
2 Rosewall, Ken (AUS)
3 Nastase, Ilie (ROM)
4 Laver, Rod (AUS)
5 Ashe, Arthur (USA)
6 Newcombe, John (AUS)
7 Lutz, Bob (USA)
8 Okker, Tom (NED)
9 Riessen, Marty(USA)
10 Gimeno, Andres (ESP)
1971
1 Newcombe, John (AUS)
2 Smith, Stan (USA)
3 Rosewall, Ken (AUS)
4 Laver, Rod (AUS)
5 Kodes, Jan (TCH)
6 Ashe, Arthur (USA)
7 Nastase, Ilie (ROM)
8 Okker, Tom (NED)
9 Drysdale, Cliff (RSA)
10 Riessen, Marty (USA)
1970
1 Newcombe, John (AUS)
2 Rosewall, Ken (AUS)
3 Roche, Tony (AUS)
4 Laver, Rod (AUS)
5 Nastase, Ilie (ROM)
6 Okker, Tom (NED)
7 Richey, Cliff (USA)
8 Smith, Stan (USA)
9 Ashe, Arthur (USA)
10 Gimeno, Andres (ESP)
1969
1 Laver, Rod (AUS)
2 Roche, Tony (AUS)
3 Newcombe, John (AUS)
4 Rosewall, Ken (AUS)
5 Okker, Tom (NED)
6 Gonzales, Pancho (USA)
7 Smith, Stan (USA)
8 Ashe, Arthur (USA)
9 Drysdale, Cliff (RSA)
10 Gimeno, Andres (ESP)
1968
1 Laver, Rod (AUS)
2 Ashe, Arthur (USA)
3 Rosewall, Ken (AUS)
4 Roche, Tony (AUS)
5 Okker, Tom (NED)
6 Newcombe, John (AUS)
7 Graebner, Clark (USA)
8 Ralston, Dennis (USA)
9 Drysdale, Cliff (RSA)
10 Gonzales, Pancho (USA)
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Explanation of points distribution from https://racketlounge.com