Sweden is not the only Nordic country where results declined …

„While average performance in mathematics declined by 31 points in Sweden between 2003 and 2012 […], performance in Finland declined by 26 points, in Iceland by 22 points, and in Denmark by 14 points.“

OECD (Hrsg.), „Resources, Policies and Practices in Sweden’s Schooling System“ (2014), S. 26