Year | Value | 2022 | 51.130141239482 | 2021 | 51.145091482734 | 2020 | 51.147325277464 | 2019 | 51.153567655919 | 2018 | 51.165400868189 | 2017 | 51.18125282602 | 2016 | 51.198422783544 | 2015 | 51.218417937841 | 2014 | 51.2361524636 | 2013 | 51.246951715479 | 2012 | 51.257074744213 | 2011 | 51.267231393176 | 2010 | 51.274417114255 | 2009 | 51.281501754578 | 2008 | 51.291054336362 | 2007 | 51.304677257433 | 2006 | 51.31840328788 | 2005 | 51.333042738318 | 2004 | 51.350417839536 | 2003 | 51.365927147059 | 2002 | 51.378097463008 | 2001 | 51.383177998042 | 2000 | 51.38657492348 | 1999 | 51.387935749715 | 1998 | 51.383092021382 | 1997 | 51.379711465156 | 1996 | 51.378465444881 | 1995 | 51.378715815476 | 1994 | 51.381432993929 | 1993 | 51.388112667726 | 1992 | 51.397121700798 | 1991 | 51.407221694387 | 1990 | 51.418360894886 | 1989 | 51.429062601074 | 1988 | 51.43815474508 | 1987 | 51.447050377661 | 1986 | 51.456897751493 | 1985 | 51.465265324705 | 1984 | 51.471481191754 | 1983 | 51.477376638155 | 1982 | 51.483474526191 | 1981 | 51.488787835368 | 1980 | 51.502253236091 | 1979 | 51.514907379091 | 1978 | 51.51821093362 | 1977 | 51.523221672379 | 1976 | 51.52901207014 | 1975 | 51.534906820266 | 1974 | 51.545219681278 | 1973 | 51.557390352626 | 1972 | 51.569010454615 | 1971 | 51.583515626707 | 1970 | 51.599034065699 | 1969 | 51.612623830046 | 1968 | 51.627663231605 | 1967 | 51.647626591807 | 1966 | 51.671125900715 | 1965 | 51.697603238096 | 1964 | 51.726848487293 | 1963 | 51.757410651206 | 1962 | 51.788907547099 | 1961 | 51.820086260473 | 1960 | 51.850545636933 |
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