Funding for this research was provided by:
Ministry of Health, Labour and Welfare (19AA2002, H30-0-014)
Received: 20 December 2020
Accepted: 28 April 2021
First Online: 17 May 2021
: This study was approved by the Ethics Committee for Epidemiological Research, Jichi Medical University (Appl. No. 18-041). The requirement for consent from study subjects was waived because this study was a secondary data analysis of a government survey.
: Not applicable.
: The authors declare that they have no competing interests.