Department of Economics, Vanderbilt University, Nashville, TN 37235, USA;
Institute for Advanced Research, Shanghai University of Finance and Economics, Shanghai 200433, China;
School of Economics and Institute for Advanced Research, Shanghai University of Finance and Economics, Shanghai 200433, China;
Department of Economics, Texas A&M University,College Station, TX 77843-1372, USA;
Institute for Advanced Research, Shanghai University of Finance and Economics, Shanghai 200433, China;