1. Centre for Economic Demography (CED) and Department of Economic History, Lund University, Box 7083, 220 07 Lund, Sweden
2. Minnesota Population Center, University of Minnesota, 50 Willey Hall, 225 19th Avenue South, Minneapolis, MN 55455, USA
3. IZA, Institute of Labor Economics, Schaumburg-Lippe-Strasse 5-9, 53113 Bonn, Germany
4. CEPR, Centre for Economic Policy Research, 33 Great Sutton Street, London EC1V 0DX, UK