Funding for this research was provided by:
Natur og Univers, Det Frie Forskningsråd (DFF - 4002-00465)
Text and Data Mining valid from 2018-05-24
Received: 27 February 2018
Accepted: 1 May 2018
First Online: 24 May 2018
Compliance with ethical standards
: The authors declare that they have no conflicts of interest.