Funding for this research was provided by:
Bundesministerium für Bildung und Forschung (FKZ 01GY1611)
Received: 14 March 2018
Accepted: 10 October 2018
First Online: 24 October 2018
Ethics approval and consent to participate
: The study is based on anonymous administrative accounts data and is thus exempt from ethical clearance according to the Ethical Review Board of the Medical Faculty of Heidelberg University.
: Not applicable.
: The authors declare that they have no competing interests.
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