Text and Data Mining valid from 2018-11-19
Received: 5 July 2018
Revised: 11 November 2018
Accepted: 12 November 2018
First Online: 19 November 2018
Change Date: 10 January 2019
Change Type: Correction
Change Details: In the original publication of this article, Fig. 2 was published incorrectly.
Compliance with ethical standards
: The authors declare that they have no conflict of interest.