Text and Data Mining valid from 2019-08-16
Received: 26 November 2018
Accepted: 1 August 2019
First Online: 16 August 2019
Ethics approval and consent to participate
: Ethical approval for each survey was obtained by the respective implementing organization in each country. More information on the ethical approval processes can be found in the survey reports and on the respective implementing organizations’ websites.
: Not applicable.
: The authors declare that they have no competing interests.