Funding for this research was provided by:
National Natural Science Foundation of China (71673083)
Article History
Received: 14 August 2020
Accepted: 2 November 2020
First Online: 23 November 2020
Compliance with ethical standards
:
: The authors declare that they have no competing interests.
: All analyses were based on published data in yearbook or literature, and no ethical approval and patient consents are required. Authors confirm that we have permission of the use of software and data in our study.
: There are no individual participants included in the study.
: The authors confirm that the work described has not been published before (except in the form of an abstract or as part of a published lecture, review, or thesis), that it is not under consideration for publication elsewhere, and that its publication has been approved (tacitly or explicitly) by the responsible authorities at the institution where the work is carried out. The copyright to the English language article is transferred to Springer effective if and when the article is accepted for publication. The authors warrant that their contributions are original and that they have full power to make this grant. The authors sign for and accept responsibility for releasing this material on behalf of any and all co-authors. The copyright transfer covers the exclusive right to reproduce and distribute the article, including reprints, translations, photographic reproductions, microform, electronic form (offline, online), or any other reproductions of similar nature.