“…Thirteen countries joined the EU in the 2000s, namely Czech Republic, Estonia, Cyprus, Latvia, Lithuania, Hungary, Malta, Poland, Slovenia and Slovakia in 2004, Bulgaria and Romania in 2007, and Croatia in 2013. 9 Due to the time difference in joining the EU, different collaboration patterns have been observed between the established 15 member states and the 13 new members (Makkonen and Mitze 2016 ). Following Makkonen and Mitze ( 2016 ), we disentangle the established 15 ‘old’ EU member states 10 which joined the EU before 2004 from the 13 ‘new’ ones.…”