Funding for this research was provided by:
The study was funded by the Government of China through Peking UniversityPeking University 985 Project Funding (985)
Received: 7 February 2020
Accepted: 15 September 2020
First Online: 24 September 2020
Ethics approval and consent to participate
: The CFPS was approved by the ethics committees of the institution of Social Science Survey, Peking University.
: Not applicable.
: We declare no competing interests.