Year	Years
1800	463.4
1950	197.3
1951	195.1
1952	190.6
1953	185.1
1954	178.7
1955	171.3
1956	163.2
1957	154.4
1958	145
1959	135.9
1969	80.2
1970	80.8
1971	81.3
1972	81.4
1973	80.9
1974	79.7
1975	77.6
1976	74.8
1977	71.2
1978	67
1979	62.4
1980	57.4
1981	52.4
1982	47.5
1983	42.9
1984	38.7
1985	35.1
1986	32
1987	29.5
1988	27.5
1989	25.9
1990	24.7
1991	23.7
1992	23.1
1993	22.6
1994	22.3
1995	22.2
1996	22.2
1997	22.2
1998	22.2
1999	22.2
2000	22.2
2001	22.2
2002	22.1
2003	22.1
2004	22
2005	21.9
2006	21.8
2007	21.6
2008	21.3
2009	20.9
2010	20.5
2011	20
2012	19.5
2013	19