Funding for this research was provided by:
Ministry of Health, Labour and Welfare (H30-kagaku-shitei-004, H25-kagaku-ippan-004, H28-kagaku-ippan 004)
Text and Data Mining valid from 2019-02-13
Received: 15 December 2018
Accepted: 6 February 2019
First Online: 13 February 2019
Compliance with ethical standards
: Horiyuki Tsuda received 3,000,000 JPY from YOG Specified Nonprofit Corporation. There are no other potential conflicts of interest.