Google Books Ngram Viewer

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

1800 - 1855 1856 - 1969 1970 - 1979 1980 - 1989 1990 - 2000 necessary conditions English
1800 - 1960 1961 - 1991 1992 - 1994 1995 - 1997 1998 - 2000 preconditions English

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