Year	per person
1800	1.138
1820	1.134
1870	1.67
1913	2.331
1950	2.943
1951	2.92
1952	3.22
1953	3.283
1954	3.297
1955	3.073
1956	3.23
1957	3.06
1958	3.409
1959	3.213
1960	3.545
1961	3.79
1962	3.641
1963	4.107
1964	4.195
1965	4.364
1966	4.367
1967	4.238
1968	4.58
1969	4.646
1970	4.823
1971	5.233
1972	6.038
1973	5.863
1974	6.186
1975	6.458
1976	6.783
1977	6.844
1978	7.129
1979	7.422
1980	7.771
1981	7.998
1982	7.808
1983	8.023
1984	8.099
1985	8.347
1986	8.019
1987	8.356
1988	8.185
1989	8.322
1990	8.81
1991	8.981
1992	9.502
1993	9.535
1994	9.671
1995	9.748
1996	10.29
1997	10.69
1998	11.07
1999	11.61
2000	12.02
2001	12.47
2002	12.55
2003	13.12
2004	13.76
2005	14.17
2006	14.78
2007	15.57
2008	16.13
2009	16.45