Google Books Ngram Viewer

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

1800 - 1817 1818 - 1853 1854 - 1868 1869 - 1979 1980 - 2008 insure English
1800 - 1861 1862 - 1987 1988 - 1995 1996 - 2002 2003 - 2008 ensure English

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