Year | Value | 2022 | 51.80739737454 | 2021 | 51.847953558388 | 2020 | 51.888734280983 | 2019 | 51.927933559673 | 2018 | 51.965995737039 | 2017 | 52.00417879666 | 2016 | 52.042458866618 | 2015 | 52.081102596246 | 2014 | 51.947545549066 | 2013 | 51.578686632321 | 2012 | 51.3696114305 | 2011 | 51.395334445385 | 2010 | 51.422512334702 | 2009 | 51.450860579017 | 2008 | 51.480497214405 | 2007 | 51.511163200744 | 2006 | 51.54367968124 | 2005 | 51.578365120293 | 2004 | 51.610460733028 | 2003 | 51.65755301451 | 2002 | 51.72924740102 | 2001 | 51.817593752845 | 2000 | 51.919079525349 | 1999 | 52.031005246653 | 1998 | 52.149129624435 | 1997 | 52.266077130511 | 1996 | 52.354060038067 | 1995 | 52.371710972714 | 1994 | 52.289929843769 | 1993 | 52.108576586594 | 1992 | 51.860812069243 | 1991 | 51.592047630646 | 1990 | 51.329732599702 | 1989 | 51.202765124493 | 1988 | 51.211446174858 | 1987 | 51.218199923442 | 1986 | 51.223470804733 | 1985 | 51.225734983056 | 1984 | 51.22776611929 | 1983 | 51.231536692004 | 1982 | 51.234338826164 | 1981 | 51.23614064522 | 1980 | 51.23706359728 | 1979 | 51.237139150209 | 1978 | 51.235848947177 | 1977 | 51.231563693953 | 1976 | 51.223381749703 | 1975 | 51.212475538472 | 1974 | 51.20065616683 | 1973 | 51.187384506403 | 1972 | 51.172727150078 | 1971 | 51.159125354454 | 1970 | 51.152131729437 | 1969 | 51.148368689087 | 1968 | 51.142214065989 | 1967 | 51.138202389229 | 1966 | 51.137563205061 | 1965 | 51.139487541542 | 1964 | 51.143866561367 | 1963 | 51.151994620925 | 1962 | 51.162350272572 | 1961 | 51.173069850468 | 1960 | 51.186174428259 |
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