Text and Data Mining valid from 2017-07-06
First Online: 6 July 2017
Compliance With Ethical Standards
: The authors declare that they have no conflict of interest.
: All procedures used in this study involving participants are in accordance with the ethical standards of the first author’s institution and with the 1964 Helsinki declaration and its later amendments.
: Informed consent was obtained from all individual participants in the study in the form of an information sheet.