Year	per person
1800	1.38
1820	1.38
1913	2.133
1950	10.05
1951	10.61
1952	10.77
1953	10.96
1954	11.43
1955	11.38
1956	11.26
1957	11.49
1958	11.56
1959	11.85
1960	12.44
1961	11.44
1962	12.12
1963	12.92
1964	13.08
1965	12.8
1966	12.8
1967	12.52
1968	13.26
1969	12.91
1970	13.51
1971	15.3
1972	15.84
1973	16.95
1974	16.84
1975	17.09
1976	18.43
1977	19.4
1978	20.42
1979	23.45
1980	22.47
1981	20.57
1982	19.94
1983	19.42
1984	19.97
1985	21.64
1986	21.88
1987	22.79
1988	23.57
1989	24.74
1990	26.2
1991	26.63
1992	28.18
1993	29.73
1994	28.79
1995	28.69
1996	31.33
1997	34.9
1998	36.71
1999	35.44
2000	33.4
2001	32.51
2002	32.75
2003	30.7
2004	29.66
2005	31.14
2006	33.04
2007	36.65
2008	36.25
2009	33.43