Received: 30 March 2021
Accepted: 29 August 2021
First Online: 11 September 2021
: Only de-identified and anonymized data was used, and therefore it is not possible to identify individual subjects in order to obtain consent. All retrieved data was publicly available, and therefore separate institutional ethical approval was not obtained nor required. All methods were carried out in accordance with relevant guidelines and regulations.
: Not applicable.
: The authors declare that they have no competing interests.