1. Tuck School of Business at Dartmouth, 100 Tuck Hall, Hanover, NH 03755, and National Bureau of Economic Research.
2. Department of Economics, New York University, 269 Mercer Street, 7th Floor, New York, NY 10003, and National Bureau of Economic Research.
3. Institute for International Economics, 1750 Massachusetts Avenue, NW, Washington, DC 20036.
4. Department of Economics, 1035 Heller Hall, University of Minnesota, 271 19th Avenue South, Minneapolis, MN 55455, Federal Reserve Bank of Minneapolis, and National Bureau of Economic Research.