Year	per person
1800	1.47
1820	1.47
1920	4.426
1921	4.234
1922	4.608
1923	4.163
1924	4.658
1925	4.539
1926	4.912
1927	4.459
1928	4.594
1929	4.311
1930	4.432
1931	4.291
1932	3.873
1933	4.525
1934	3.917
1935	4.163
1936	4.361
1937	4.911
1938	5.114
1939	5.089
1940	4.805
1941	5.295
1942	4.6
1943	4.522
1944	3.976
1945	4.4
1946	4.795
1947	5.548
1948	5.709
1949	5.787
1950	5.35
1951	5.318
1952	5.761
1953	6.412
1954	6.239
1955	6.704
1956	6.272
1957	6.557
1958	7.099
1959	7.081
1960	7.401
1961	7.42
1962	7.59
1963	7.955
1964	8.071
1965	8.521
1966	8.881
1967	9.127
1968	9.531
1969	9.872
1970	10.23
1971	10.6
1972	11.22
1973	11.77
1974	12.07
1975	11.98
1976	12.28
1977	13
1978	13.27
1979	13.52
1980	13.38
1981	12.76
1982	11.54
1983	11.53
1984	12.08
1985	11.83
1986	12.12
1987	12.35
1988	12.43
1989	12.81
1990	12.94
1991	12.91
1992	13.51
1993	13.98
1994	14.27
1995	14.29
1996	14.13
1997	14.64
1998	15.58
1999	16.75
2000	16.83
2001	16.73
2002	16.94
2003	17.76
2004	18.21
2005	18.99
2006	20.24
2007	21.41
2008	21.58
2009	20.95