Text and Data Mining valid from 2019-09-05
Received: 4 April 2019
Accepted: 12 August 2019
First Online: 5 September 2019
Ethics approval and consent to participate
: Due to the nature of the study and dataset, it was not necessary to obtain informed consent or approval from an institutional ethics committee.
: The authors give consent to publish the manuscript.
: The authors declare that they have no competing interests.