Li, Xingwei http://orcid.org/0000-0002-8853-356X
Huang, Yicheng http://orcid.org/0000-0002-0293-6844
Li, Xiangxue
Liu, Xiang
Article History
Received: 20 May 2023
Accepted: 30 August 2023
First Online: 16 September 2023
Competing interests
: The authors declare no competing interests.
: Our study was not medical research nor employed any experiments on humans, i.e., the study did not involve human participants. We collect data by accessing statistical yearbooks. Hence, according to the Declaration of Helsinki, the ethical issue should not be a problem in our study.
: Not applicable.