English is (to her credit) widely considered a language of .. mixed breeding, seeing as to how she accepts favours from just about anybody and everybody. What I'd like to know is how and by how much has the vocabulary grown since the late Middle Ages (~15th century Middle English)? This was before Shakespeare, the Renaissance, colonialism, and well, science & technology. Are there any related statistics available on this subject, and perhaps also on the number of loanwords in modern English?
Regarding your questions, chapter 6 (by John Algeo) of The Cambridge History of the English Language: 1776-1997 (ISBN 0521264774) provides a few statistics as well as extensive background information about English vocabulary. See particularly section 2.2, "The growth of the vocabulary", and subsections 2.2.1, "The size of the vocabulary" and 2.2.3, "Gauging changes in the size of the vocabulary". As noted in the middle paragraph of the following snippet, about 3/4 of the 80000+ words listed in Finkenstaedt et al's Chronological English Dictionary are post-Middle English (M.E. is the English language as written and spoken c.1100-c.1500.) I've left portions of adjacent paragraphs visible to reinforce Algeo's warnings that these statistics are subject to systematic bias.