Received: 9 January 2019
Accepted: 23 April 2019
First Online: 14 May 2019
Ethics approval and consent to participate
: The ethical committee of the Canton of Zurich stated no objections to the study (BASEC-2017-00598), see p.5, lines 24–26 of the manuscript.
: All data was collected anonymously with no possibility to identify individual persons. Participants were informed about the aim of the study and confidentiality at the beginning of the questionnaire.
: All authors declare that they have no competing interests.
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