1. GESIS—Leibniz Institute for the Social Sciences, Mannheim, Baden-Wurttemberg, Germany
2. Technical University of Kaiserslautern, Kaiserslautern, Germany
3. Federal Statistical Office of Germany (Destatis), Wiesbaden, Germany
4. Utrecht University, Utrecht, the Netherlands
5. Center for Science and Research Management, Speyer, Rhineland-Palatinate, Germany