1. Instituto de Economía, Facultad de Ciencias Económicas y de Administración, Universidad de la República, Joaquín Requena 1375, Montevideo, CP 11200, Uruguay (e-mail: )
2. Queen Mary University of London, Mile End Road, E1 4NS, London, United Kingdom, Centre for Economic Performance (London School of Economics), Centre for Economic Policy Research and Institute for the Study of Labor (e-mail: )
3. University of California at Berkeley, Department of Economics, 530 Evans Hall #3880 Berkeley, CA 94720 and National Bureau of Economic Research (e-mail: )