To try to put this in perspective, I will label their slams, etc. AT THE TIME OF THE RESPECTIVE END-OF-YEAR RANKINGS.
1985:
1 Lendl, Ivan (TCH) -- 2 slams (1 FO, 1 USO)
2 McEnroe, John (USA) 7 slams (3 Wimbledon, 4 USO)
3 Wilander, Mats (SWE) 3 slams (2 AO, 1 FO)
4 Connors, Jimmy (USA) 8 slams (1 AO, 2 Wimbledon, 5 USO)
5 Edberg, Stefan (SWE) 1 slam (1 AO)
6 Becker, Boris (GER) 1 slam (1 Wimbledon)
7 Noah, Yannick (FRA) 1 slam (1 FO)
8 Järryd, Anders (SWE) 0 slams
9 Mecir, Miloslav (TCH) 0 slams (didn't make first finals appearance until following year)
total = 23 slams by 7 players.
1990:
1 Edberg, Stefan (SWE) 4 slams (2 AO, 2 Wimbledon)
2 Becker, Boris (GER) 4 slams (3 Wimbledon, 1 USO)
3 Lendl, Ivan (TCH) 8 slams (2 AO, 3 FO, 3 USO)
4 Agassi, Andre (USA) 0 slams
5 Sampras, Pete (USA) 1 slam (1 USO)
6 Gomez, Andres (ECU) 1 slam (1 FO)
7 Muster, Thomas (AUT) 0 slams
8 Sanchez, Emilio (ESP) 0 slams
9 Ivanisevic, Goran (YUG) 0 slams
10 Gilbert, Brad (USA) 0 slams
total = 18 slams by 5 players
1995:
1 SAMPRAS, PETE 7 slams (1 AO, 3 Wimbledon, 3 USO)
2 AGASSI, ANDRE 3 slams (1 AO, 1 Wimbledon, 1 USO)
3 MUSTER, THOMAS 1 slam (1 FO)
4 BECKER, BORIS 5 slams (1 AO, 3 Wimbledon, 1 USO)
5 CHANG, MICHAEL 1 slam (1 FO)
6 KAFELNIKOV, YEVGENY 0 slams
7 ENQVIST, THOMAS 0 slams
8 COURIER, JIM 4 slams (2 AO, 2 FO)
9 FERREIRA, WAYNE 0 slams
10 IVANISEVIC, GORAN 0 slams
total = 21 slams by 6 players
2000:
1 Kuerten, Gustavo 2 slams (2 FO)
2 Safin, Marat 1 slam (1 USO)
3 Sampras, Pete 13 slams (2 AO, 7 Wimbledon, 4 USO)
4 Norman, Magnus 0 slams
5 Kafelnikov, Yevgeny 2 slams (1 FO, 1 AO)
6 Agassi, Andre 6 slams (2 AO, 1 FO, 1 Wimbledon, 2 USO)
7 Hewitt, Lleyton 0 slams
8 Corretja, Alex 0 slams
9 Enqvist, Thomas 0 slams
10 Henman, Tim 0 slams
total = 24 slams by 5 players
2005:
1 Federer, Roger 6 slams (1 AO, 3 Wimbledon, 2 USO)
2 Nadal, Rafael 1 slam (1 FO)
3 Roddick, Andy 1 slam (1 USO)
4 Hewitt, Lleyton 2 slams (1 Wimbledon, 1 USO)
5 Davydenko, Nikolay 0 slams
6 Nalbandian, David 0 slams
7 Agassi, Andre 8 slams (4 AO, 1 FO, 1 Wimbledon, 2 USO)
8 Coria, Guillermo 0 slams
9 Ljubicic, Ivan 0 slams
10 Gaudio, Gaston 1 slam (1 FO)
total = 19 slams by 6 players (change it to 21 by 7 players if Safin weren't a complete flake)
I think that people take a snapshot of one of these years, like 1985, and go "Look at all the hall-of-famers" without recognizing that these guys were not all at identical points in their career. Some were on the upswing, others were on the downswing. 10 years from now we might look at 2006 the same way and say "Look, Federer had to compete against all those hall-of-fame caliber players."