Received: 24 November 2017
Accepted: 30 July 2019
First Online: 14 August 2019
Ethics approval and consent to participate
: The study protocol was approved by the Ethics Committee of the Faculty of Human Sciences of the University of Bern (Protocol No 2012–6-140960). Informed consent was obtained in written form from all individual participants included in the study.
: Not applicable.
: The authors declare that they have no competing interests.