1. Paris School of Economics, 48 Boulevard Jourdan, 75014 Paris, Oxford, and CONICET (e-mail: )
2. Paris School of Economics, 48 Boulevard Jourdan, 75014 Paris, and Iddri Sciences Po (e-mail: )
3. Paris School of Economics, 48 Boulevard Jourdan, 75014 Paris (e-mail: )
4. University of California, Berkeley, CA 94720, and NBER (e-mail: )