1. a Economic and Social Development , Institute of Ethnology and Anthropology, Chinese Academy of Social Sciences , Bldg.6, 27, Zhongguancun Nandajie, Beijing, 100081, China
2. b Department of Economics , University of Winnipeg , 515 Portage Ave., Winnipeg, Manitoba, R3B 2E9, Canada
3. c School of Economics and Business and Administration, Beijing Normal University , Beijing, 100875, China