Received: 26 April 2021
Accepted: 17 September 2021
First Online: 11 October 2021
: The study was granted ethical approval by the National Center for Health Statistics (NCHS). The study was carried out in accordance with the ethical standards of the responsible committee on human experimentation and with the 1975 Helsinki Declaration and its later amendments. Furthermore, written informed consent was received from each subject.
: Not applicable.
: The author declares no competing interests.