Funding for this research was provided by:
Samenwerkende Gezondheidsfondsen (-)
Received: 11 January 2019
Accepted: 26 September 2019
First Online: 11 November 2019
Ethics approval and consent to participate
: Due to the non-invasive character of this study, no ethical approval was needed.
: Not applicable (since no individual data was gathered).
: All authors declare that they have no competing interests.