Year	per person
1800	1.28
1820	1.28
1920	4.52
1921	4.446
1922	4.646
1923	4.445
1924	4.051
1925	4.718
1926	4.598
1927	4.993
1928	5.491
1929	5.32
1930	5.548
1931	5.551
1932	4.872
1933	4.48
1934	4.297
1935	4.027
1936	4.021
1937	3.773
1938	3.92
1939	3.958
1940	4.117
1941	4.038
1942	3.599
1943	3.576
1944	3.569
1945	4.327
1946	4.548
1947	4.732
1948	4.724
1949	4.652
1950	4.661
1951	4.772
1952	4.813
1953	5.044
1954	4.613
1955	4.589
1956	4.805
1957	4.869
1958	4.864
1959	4.828
1960	4.961
1961	4.919
1962	5.024
1963	5.029
1964	5.102
1965	5.347
1966	5.46
1967	5.566
1968	5.69
1969	5.534
1970	5.523
1971	5.545
1972	5.548
1973	5.611
1974	6.194
1975	6.147
1976	6.568
1977	7.025
1978	7.464
1979	7.551
1980	7.318
1981	7.209
1982	6.846
1983	6.574
1984	6.6
1985	6.652
1986	6.475
1987	6.63
1988	6.739
1989	6.782
1990	6.59
1991	6.577
1992	6.758
1993	7.028
1994	6.694
1995	6.741
1996	6.787
1997	6.931
1998	6.948
1999	6.642
2000	6.784
2001	6.784
2002	6.798
2003	6.864
2004	7.038
2005	7.162
2006	7.483
2007	7.783
2008	7.928
2009	7.617