Text and Data Mining valid from 2018-08-15
Received: 18 May 2018
Revised: 18 June 2018
Accepted: 28 June 2018
First Online: 15 August 2018
Compliance with ethical standards
: Prof. Francesco Sardanelli.
: All the authors have no competing interests related to the present paper to disclose.
: Data originating the Tables are available on request sent to the corresponding author.