Year	per person
1800	1.613
1820	1.62
1913	2.78
1950	3.082
1951	3.204
1952	3.324
1953	3.445
1954	3.582
1955	3.716
1956	3.855
1957	4.007
1958	4.156
1959	4.311
1960	4.473
1961	4.647
1962	4.822
1963	5.006
1964	5.194
1965	5.389
1966	5.597
1967	5.811
1968	6.033
1969	6.229
1970	6.428
1971	6.644
1972	6.872
1973	7.091
1974	7.325
1975	7.563
1976	7.818
1977	8.076
1978	8.347
1979	8.623
1980	8.91
1981	9.21
1982	9.509
1983	9.831
1984	10.16
1985	10.49
1986	10.85
1987	11.2
1988	11.57
1989	11.96
1990	12.36
1991	12.77
1992	13.2
1993	13.64
1994	14.1
1995	14.58
1996	15.08
1997	15.59
1998	16.4
1999	17.25
2000	16.64
2001	12.83
2002	9.902
2003	8.32
2004	8.036
2005	7.768
2006	7.157
2007	6.845
2008	6.764