Funding for this research was provided by:
Ministry of Health, Labour and Welfare (H29-shinkougyousei-shitei-005)
Received: 14 September 2019
Accepted: 24 February 2020
First Online: 28 February 2020
Ethics approval and consent to participate
: Not applicable because no individual data in any form have been reported in this article.
: Not applicable.
: All authors declare no support from any organization for the submitted work; no financial relationships with any organizations that might have an interest in the submitted work in the previous 3 years; and no other relationships or activities that could appear to have influenced the submitted work.