1. Social Policy Department, the European Institute and LSE Health, London School of Economics, Cowdray House, Houghton Street, WC2A 2AE, UK,
2. Departament d'Economia i Impresa, Universitat Pompeu Fabra, Ramon Trias Fargas 25-27, 08005 Barcelona, Spain
3. Departament de Teoria Econòmica, Universitat de Barcelona, Torre 2, Planta 1a and 2a, Av. Diagonal 690, 08034 Barcelona, Spain