Funding for this research was provided by:
Economic and Social Research Council (ES/H037977/1)
Text and Data Mining valid from 2018-04-16
Received: 13 September 2017
Accepted: 4 April 2018
First Online: 16 April 2018
Ethics approval and consent to participate
: Ethics approval and participant consent was not necessary as this study involved the use of a previously-published de-identified database held by the UK data archive.
: The authors declare that they have no competing interests.
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