Raya Muttarak1, Nadia Steiber2, Silvano Gallus3. 1. Wittgenstein Centre for Demography and Global Human Capital, International Institute for Applied Systems, Analysis, Laxenburg, Austria. Electronic address: muttarak@iiasa.ac.at. 2. Department of Economic Sociology, University of Vienna, Vienna, Austria. 3. Department of Epidemiology, IRCCS-Istituto di Ricerche Farmacologiche Mario Negri, Milan, Italy.