1. Eurostat, European Commission, 5, rue Alphonse Weicker, L-2721 Luxembourg, Luxembourg
2. Engineering and Management Department at Instituto Superior Técnico (IST), University of Lisbon, Av. Rovisco Pais 1, 1049-001 Lisboa, Portugal
3. NOVA Information Management School (NOVA IMS), Universidade Nova de Lisboa, Campus de Campolide, 1070-312 Lisboa, Portugal
4. Lisbon School of Economics and Management, University of Lisbon, Campus de Campolide, 1070-312 Lisboa, Portugal