1. Institute for International Economic Studies, Stockholm University, S-106 91 Stockholm, Sweden, CEPR, CESIfo, and IZA.
2. Department of Economics, Universitat Pompeu Fabra, Ramón Trías Fargas 25-27, 08005 Barcelona, Spain, and CEPR.
3. Institute for International Economic Studies, Stockholm University, S-106 91 Stockholm, Sweden, and CEPR.
4. Department of Economics, University College London, Gower Street, London WC1E 6BT, United Kingdom, CEPR, and Institute for Economic Studies, Stockholm University.