1. School of Finance, Southwestern University of Finance and Economics, Chengdu, Sichuan 611130, China
2. Department of Economics, University of Kansas, Lawrence, KS, 66045, USA
3. Wang Yanan Institute for Studies in Economics, Ministry of Education Key Laboratory of Econometrics and Fujian Key Laboratory of Statistical Sciences, Xiamen University, Xiamen, Fujian 361005, China