Funding for this research was provided by:
National Natural Science Foundation of China (71874052)
Received: 19 October 2021
Accepted: 13 May 2022
First Online: 29 July 2022
: Not applicable as the data in this paper is statistical data available on the Internet or data obtained through crawler technology. All methods used were in accordance with the Declaration of Helsinki.
: Not applicable.
: The authors declare that they have no competing interests.