After publication of this work , we noted that we inadvertently failed to include the complete list of all coauthors. The full list of authors has now been added and the Authors' contributions and Competing interests section modified accordingly.
The authors declare that they have no competing interests. GF declares no competing interests.
RP did the primary data analysis and prepare the initial and subsequent versions of the manuscript; SA supervised the data analysis and preparation of the results table and commented on versions of the manuscripts. GF supervised the data analysis and statistical evaluation; KM conceived the study, reviewed the data and draft versions of the manuscript.