1. Department for Sports Science and Sport, Friedrich-Alexander University of Erlangen-Nuremberg, Gebbertstrasse 123b, 91058 Erlangen, Germany
2. Centre for Health Economics (CHE), University of York, Heslington, York, YO10 5DD, UK
3. Luxembourg Institute of Socio-Economic Research (LISER), Maison des Sciences Humaines, 11 Porte des Sciences, L-4366 Esch-sur-Alzette, Luxembourg