Google Books Ngram Viewer

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

1970 - 1987 1988 - 2004 2005 2006 2007 - 2008 irregular immigration English
1970 - 1978 1979 - 1998 1999 - 2000 2001 - 2006 2007 - 2008 illegal immigration English

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