Funding for this research was provided by:
Major Research Plan (71433005)
Received: 14 August 2019
Accepted: 4 February 2020
First Online: 6 February 2020
Ethics approval and consent to participate
: This study used secondary data collected from open source available to every researcher. Data are freely downloadable at the official website (ExternalRef removed). Therefore, we believe that ethical approval and consent to participate are not applicable.
: Not applicable.
: The authors have no competing interests to declare.