You have to go back a bit further than 50 years for that. The 1960s and 70s were the period of peak immigration from Finland to Sweden. Finland was a poor country with too many young people and too few opportunities, while Sweden had jobs and generous welfare policies. Many of the migrants could not integrate into the society, and too many of them ended up abusing drugs and alcohol and committing crime.

What happens now seems to be the same thing on a larger scale.