Funding for this research was provided by:
Norges Forskningsråd (238970)
Text and Data Mining valid from 2018-06-19
Received: 26 January 2018
Accepted: 1 June 2018
First Online: 19 June 2018
: The authors declare that they have no competing interests.
: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.