1. ZEW - Leibniz Centre for European Economic Research, University of Mannheim and MEA, L7,1, D-68161 Mannheim, Germany
2. Munich Center for the Economics of Aging (MEA), Max Planck Society, Amalienstr. 33, D-80799 Munich, Germany
3. Institute for Evaluation of Labour Market and Education Policy (IFAU), P.O. Box 513, SE-751 Uppsala, Sweden