Harvard University - T.H. Chan School of Public Health, Tsinghua University, University of North Carolina (UNC) at Chapel Hill, Chinese Academy of Medical Sciences & Peking Union Medical College (CAMS & PUMC), Vienna University of Economics and Business - Department of Economics, Austrian Academy of Sciences - Vienna Institute of Demography, Chinese Academy of Medical Sciences & Peking Union Medical College (CAMS & PUMC), Heidelberg University and Heidelberg University