Year	Years
1800	450.6
1950	167.3
1951	165.3
1952	161.9
1953	158.3
1954	154.5
1955	150.6
1956	146.6
1957	142.4
1958	138.1
1959	133.9
1960	129.8
1961	125.7
1962	121.7
1963	117.7
1964	113.8
1965	110
1966	106.2
1967	102.5
1968	98.9
1969	95.53
1970	92.35
1971	88.8
1981	57.3
1982	58
1983	58.5
1984	58.8
1985	58.8
1986	58.3
1987	57.7
1988	56.9
1989	56.1
1990	55.4
1991	55
1992	54.9
1993	54.9
1994	55.1
1995	55.3
1996	55.4
1997	55.4
1998	55
1999	54.2
2000	53.1
2001	52
2002	50.7
2003	49.5
2004	48
2005	46.7
2006	45.4
2007	44.1
2008	42.8
2009	41.4
2010	40.2
2011	38.9
2012	37.6
2013	36.4