Funding for this research was provided by:
Ekonomiaren Garapen eta Lehiakortasun Saila, Eusko Jaurlaritza
Text and Data Mining valid from 2019-04-17
Received: 26 December 2018
Accepted: 5 April 2019
First Online: 17 April 2019
Compliance with ethical standards
: The authors declare that they have no conflict of interest.