This graph shows the variable numbers of quotations in OED used to illustrate words and meanings dated between 1150 and 1899 (OED sets out to record the English language from 1150; see Murray's 'General Explanations', p. viii of 1933 edition of OED1, reproduced at http://dictionary.oed.com/archive/oed2-preface/general.html [accessed 8 August 2005]).

The number rises from a low point at the start of the historical period covered (with few sources available), to a high point towards the end. The next two pages divide the data into two separate periods...