Year	Years
1951	194.5
1952	183.8
1953	173.5
1954	163.9
1955	154.8
1956	145.8
1957	137
1958	128.4
1959	120.1
1960	112
1961	104.2
1962	96.6
1963	89.6
1964	82.9
1965	76.6
1966	70.7
1967	65.3
1968	60.3
1969	55.7
1970	51.6
1971	48
1972	44.9
1973	42.2
1974	40
1975	38.2
1976	36.6
1977	35.3
1978	34.1
1979	33
1980	31.9
1981	30.9
1982	29.9
1983	29
1984	28.1
1985	27.3
1986	26.5
1987	25.8
1988	25.2
1989	24.8
1990	24.4
1991	24
1992	23.6
1993	23.2
1994	22.5
1995	21.8
1996	20.8
1997	19.8
1998	18.7
1999	17.7
2000	16.8
2001	16
2002	15.2
2003	14.4
2004	13.7
2005	12.9
2006	12.2
2007	11.5
2008	10.9
2009	10.4
2010	9.9
2011	9.5
2012	9.1
2013	8.8