1. Department of Economics, University of Toronto, 150 St. George Street, Toronto, ON M5S 3G7, Canada (email: )
2. Department of Economics, KU Leuven, Naamsestraat 69, 3000 Leuven, Belgium, and CEPR (email: )
3. Department of International Economics and Trade, Xiamen University, Economics Building, 361005 Xiamen, China, and Wang Yanan Institute for Studies in Economics (email: )
4. Department of Economics, Chinese University of Hong Kong, Shatin, N.T., Hong Kong (email: )