Capital Medical University - School of Public Health, Government of the People's Republic of China - National Health Commission (formerly National Health and Family Planning Commission), Health Commission of Shaanxi Province - Center of Health Information, Health Commission of Shaanxi Province - Center of Health Information, Health Commission of Shaanxi Province - Center of Health Information, Health Commission of Shaanxi Province - Office of Planning Information, Capital Medical University - Department of Epidemiology and Health Statistics, Dalian University and Government of the People's Republic of China - National Health Commission (formerly National Health and Family Planning Commission)