Year	per person
1800	1.256
1820	1.298
1913	3.844
1950	6.405
1970	13.87
1971	15.63
1972	16.72
1973	17.21
1974	16.86
1975	14.15
1976	16.84
1977	19.51
1978	20.92
1979	22.82
1980	23.91
1981	24.33
1982	25.58
1983	26.59
1984	28.55
1985	29.54
1986	30.31
1987	32.09
1988	34.39
1989	36.63
1990	38.54
1991	37.8
1992	40.27
1993	39.57
1994	41
1995	44.25
1996	44.36
1997	44.76
1998	46.43
1999	48.14
2000	50.05
2001	51.47
2002	51.94
2003	52.12
2004	53.1
2005	53.67
2006	54.62
2007	56.52
2008	57.78
2009	56.24