17 years in Denmark and I have never been shown aggression by any other road user. I usually ride about 11000km a year. I would be interested to hear what experience other Scandanavian riders have.
I think a lot of this rage has nothing to do with if you are in a car or on a bike. Its just the make up of the people. Watch a Danish football match and see the difference between the Danish fans and English fans. Danish fans are called Roligans. It is a mickey take of Hooligan as Rolig means quiet.
Everyone in Scandanavia seems friendly and calm with nothing to prove. It seems to be the opposite in the UK.