1. Institute of Economics, Centre for Economic and Regional Studies, Budapest 1097, Hungary;
2. Institute of Operations and Decision Sciences, Corvinus University of Budapest, Budapest 1093, Hungary;
3. Institute for Economic Analysis (IAE-CSIC), 08193 Barcelona, Spain;
4. Barcelona School of Economics, 08005 Barcelona, Spain;
5. Institute for Systems and Computer Engineering, Technology and Science, 4200-465 Porto, Portugal;
6. Polytechnic of Porto–School of Engineering, 4249-015 Porto, Portugal