Article History
Received: 12 August 2019
Accepted: 19 May 2020
First Online: 11 June 2020
Ethics approval and consent to participate
: Because anonymised data from a public use file were used, a formal ethical consultation and consent to participate were not required.
: Not applicable as this analysis is based on anonymised data from a public use file.
: All authors declare that they have no competing interests.