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Sweden 
Sweden shares the tradition of Nordic folk dance music with its neighbouring countries, including polka, schottische, waltz, polska and mazurka. The accordion, clarinet, fiddle and nyckelharpa are among the most common Swedish folk instruments. This instrumental genre is the biggest one in Swedish traditional music. In the 1960s, Swedish youth sparked a roots revival in Swedish folk culture. Many joined Spelmanslag (folk musicians' clubs) and performed on mainstream radio and TV. They focused on instrumental polska music, with vocals and influences from other traditional genres becoming more prominent since the 1990s.
Since the fifties Swedish popmusic made a start with the instrumental surfband The Spotnicks from Göteborg who were founded on 1957. They were joined by local rock ‘n roll hero Jerry Williams and beatgroups like the Hep Stars and Tages. Later on the Hep Stars will ad members to Svenne & Lotta as well as to Abba. But before Abba hits the international music scene there is a political influenced folkmusic at the start of the sixties working through in the seventies. This music scene is known as Progg (not to be confused with progressive rock). It was a movement that was influenced by the hippie ideals and mixed them with left wing ideology. They mixed folklore with rock and pop. Groups like International Harvester, Träd, Gräs och Stenar and singers like Mikael Wihle, Björn Afzelius and Ulf Dageby openly criticized the war in Vietnam and other social and political mishaps. Their highpoint was in 1970 with the two day festival Diaphragm i Stockholm. Though not keen on commercial labels a number of artists who often tend to belong to progg movement moved during the seventies to a commercial record label. Artists like John Holmes, Ola Magnell, Peps Persson, Mikael Ramel, Bernt Staf, Hoola Bandoola Band, and Lasse Tennander gained some broader recognition this way.
But then in 75 Abba wins the Eurovision. With ABBA, Sweden entered into a new era, in which Swedish pop music gained international prominence after winning the 1974 Eurovision Song Contest. They sold a total of 380 million records around the world, making them the second-most successful group ever, after The Beatles and continue to sell 3000[minimum] albums a year worldwide.