Data derived from the processing of British National Corpus (BNC) data collections:

Leech, G. (1992). 100 million words of English: the British National Corpus (BNC). Language research, 28(1), 1-13.

BNC Consortium (2001). The British National Corpus, version 2 (BNC World). Distributed by Oxford University Computing Services on behalf of the BNC Consortium. URL: http://www.natcorp.ox.ac.uk/.