Funding for this research was provided by:
Norges Forskningsråd (257019)
Text and Data Mining valid from 2019-11-05
Received: 16 May 2018
Accepted: 11 September 2019
First Online: 5 November 2019
Compliance with Ethical Standards
: This study was approved by the Norwegian Centre for Research Data (NSD), reference number 48366. Approval from NSD is the appropriate level of ethical review according to Norwegian law.
: The authors declare that they have no conflict of interest.