1946	1.63	
1947	2.16	
1948	2.77	
1949	2.77	
1950	2.77	
1951	2.77	
1952	2.77	
1953	2.92	
1954	2.99	
1955	2.93	
1956	2.94	
1957	3.14	
1958	3.00	
1959	3.00	
1960	2.91	
1961	2.85	
1962	2.85
1963	2.91	
1964	3.00	
1965	3.01	
1966	3.10	
1967	3.12	
1968	3.18	
1969	3.32	
1970	3.39	
1971	3.60	
1972	3.60	
1973	4.75	
1974	9.35	
1975	12.21	
1976	13.10	
1977	14.40	
1978	14.95	
1979	25.10	
1980	37.46
1981	35.75	
1982	31.83	
1983	29.08	
1984	28.75	
1985	26.92	
1986	14.44	
1987	17.75	
1988	14.87	
1989	18.33	
1990	23.19	
1991	20.20	
1992	19.25	
1993	16.75	
1994	15.66	
1995	16.75	
1996	20.46	
1997	18.64	
1998	11.91	
1999	16.56	
2000	27.39	
2001	23.00	
2002	22.81	
2003	27.69	
2004	37.66	
2005	50.04	
2006	58.30	
2007	64.20	
2008	91.48	
2009	53.48	
2010	71.21