Funding for this research was provided by:
Received: 10 October 2017
Accepted: 26 March 2018
First Online: 11 April 2018
Ethics approval and consent to participate
: This study uses public data collected in a survey for official statistics. All subjects gave their informed consent to participate in the survey; the data collection protocol and the questionnaire were approved by the Commission Nationale de l’Informatique et des Libertés (National commission for liberty and informatics) (N°1,179,915).
: Not applicable.
: The authors declare that they have no competing interests.
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