Funding for this research was provided by:
The public welfare research project of Zhejiang province (LGF18H150005)
Scientific research project of Zhejiang Education Commission (Y201737841)
Text and Data Mining valid from 2018-12-01
Received: 6 September 2018
Accepted: 26 November 2018
First Online: 18 December 2018
Ethics approval and consent to participate
: This study was an analysis of the third-party anonymized databases with pre-existing IRB approval.
: Not applicable.
: The authors declare that they have no competing interests.
: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.