SPD – Sozialdemokratische Partei Deutschlands... With more than 600,000 members it is the largest party in Germany.
It is quite possible that smaller countries has larger percentage involved in parties. But the reason I got quite surprised is that the "death of the parties" in Sweden is quite a big subject. Using the numbers provided by wikipedia (my previous comment), in 1962 18% of the population was members of a political party. From there: 1962 18% 1970 17% 1979 19% 1991 7% 2000 4% 2006 3,3%
The big loss during between 79 and 91 was in mainly due to the right bloc governments action in untieing the links between the mayor unions and the socialdemocratic party. Until 1991, if you became member of a union belonging to LO, you also became a member of the socialdemocratic party. But since then all the big parties has lost a lot of members, giving some problems to find candidates for local elections and such. At current rate the political parties will be empty in 2020...
If this is a general trend in western Europe (or a larger area) it is worth exploring. A vote for PES is a vote for EPP! A vote for EPP is a vote for PES! Support the coalition, vote EPP-PES in 2009!