Google Books Ngram Viewer

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

1800 - 1837 1838 - 1932 1933 - 1945 1946 - 1976 1977 - 2008 insure English
1800 - 1835 1836 - 1993 1994 - 1998 1999 - 2003 2004 - 2008 ensure English

Run your own experiment! Raw data is available for download here.
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