Google Books Ngram Viewer

Graph these comma-separated phrases:
case-insensitive
between and from the corpus with smoothing of .  
Search in Google Books:

1800 - 1918 1919 - 1947 1948 - 1954 1955 - 1988 1989 - 2000 carbon copy English
1800 - 1980 1981 - 1997 1998 1999 2000 blind carbon copy English

Run your own experiment! Raw data is available for download here.
© 2013 Google - Privacy & Terms - About Google - About Google Books - About Ngram Viewer