I guess all the top players of the past have grown older and contracted injuries and no younger players have come up to replace them. A couple of years ago, Enqvist was dominant on hard and indoor courts while Norman was a powerful force on clay; now injuries have wrecked both their careers and look like doing the same to Johansson, while Bjorkman's style of game has arguably become outdated in the modern era. Even Vinciguerra, the only young Swede at the top of the game, is suffering with repeated injuries.
Mind you, Joachim Johansson pushed Arthurs close during their dead rubber in Davis Cup in April. As a 6'5" big server, he's arguably rather atypical when you consider the players that Sweden have produced in the past.
Everyone is injured, as Sjengster noted, and the forces on the horizon -- Robin Soderling and Joachim Johansson, most notably -- are still on the horizon for the moment. If Thomas Johansson can ever come back from his knee problems, I think he could return to the Top 50.
Korben -- about time Finland was recognized for a great player
Nordics are Danes/Swedes and Norweigans
as their language is more or less pretty similar
Icelandics are also part of these 3 but they are also not Nordics. There was a thread about this in Non-Tennis sometime ago.
Fins are in a world of their own. its not their fault they are stuck where they are.