Google Books Ngram Viewer

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

1900 - 1939 1940 - 2001 2002 - 2003 2004 - 2005 2006 - 2008 terrorism English
1900 - 1934 1935 - 1961 1962 - 1967 1968 - 1999 2000 - 2008 communism English

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