Google Books Ngram Viewer

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

1800 - 1951 1952 - 1974 1975 - 1978 1979 - 1994 1995 - 2000 per capita income English
1800 - 1947 1948 - 1975 1976 - 1980 1981 - 1993 1994 - 2000 income per capita English
1800 - 1881 1882 - 1971 1972 - 1979 1980 - 1988 1989 - 2000 average income English
1800 - 1939 1940 - 1966 1967 1968 - 1987 1988 - 2000 income per person English

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