Text and Data Mining valid from 2018-02-10
Received: 8 December 2017
Accepted: 29 January 2018
First Online: 10 February 2018
Compliance with ethical standards
: The study used a data set that is available online in the public domain; hence, there was no need to seek ethical consent to publish this study.
: This article does not contain any studies with human or animal subjects performed by the author.
: The authors declare that they have no conflict of interest.