Year	per person
1800	0.908
1820	0.908
1913	1.403
1950	2.418
1951	2.498
1952	2.518
1953	2.556
1954	2.638
1955	2.658
1956	2.694
1957	2.73
1958	2.738
1959	2.825
1960	3.133
1961	3.446
1962	4.071
1963	4.196
1964	4.692
1965	5.286
1966	5.37
1967	5.73
1968	5.325
1969	5.405
1970	6.825
1971	6.754
1972	7.379
1973	7.569
1974	8.192
1975	8.254
1976	8.287
1977	8.293
1978	8.255
1979	8.117
1980	8.037
1981	8.318
1982	8.543
1983	8.295
1984	8.171
1985	8.372
1986	8.362
1987	8.739
1988	8.142
1989	8.306
1990	8.163
1991	7.996
1992	7.792
1993	7.809
1994	8.028
1995	8.271
1996	8.38
1997	8.502
1998	8.597
1999	8.749
2000	8.818
2001	8.874
2002	9.053
2003	9.225
2004	9.399
2005	9.614
2006	9.856
2007	10.16
2008	10.36
2009	10.37