Google has a neat & simple tool online as part of their massive Google Books undertaking called the ‘Ngram Viewer’. Simply enter a comma-delimited list of words and see the frequency of those words in printed literature going back to the 1800’s and earlier. In the example above I compare ‘napoleon’ to ‘caesar’, and you can see how prior to 1920 Napoleon was pretty popular, but afterwards Caesar takes over.
The “Google Million”. All are in English with dates ranging from 1500 to 2008. No more than about 6000 books were chosen from any one year, which means that all of the scanned books from early years are present, and books from later years are randomly sampled. The random samplings reflect the subject distributions for the year (so there are more computer books in 2000 than 1980). Books with low OCR quality were removed, and serials were removed.
