Google Books Ngram Viewer

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

1920 - 1975 1976 - 1999 2000 - 2002 2003 - 2005 2006 - 2008 problem finding English
1920 - 1956 1957 - 1995 1996 - 1999 2000 - 2004 2005 - 2008 problem solving English
1920 - 1950 1951 - 1999 2000 - 2002 2003 - 2005 2006 - 2008 critical thinking English

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