Year | Value | 2022 | 49.456287783788 | 2021 | 49.463765245196 | 2020 | 49.49265586106 | 2019 | 49.541214471515 | 2018 | 49.613884926296 | 2017 | 49.692169046151 | 2016 | 49.773430331009 | 2015 | 49.862422494864 | 2014 | 49.956858552323 | 2013 | 50.058362670302 | 2012 | 50.159066808059 | 2011 | 50.256014719685 | 2010 | 50.352476649004 | 2009 | 50.447061898006 | 2008 | 50.563909774436 | 2007 | 50.688309983308 | 2006 | 50.751483190508 | 2005 | 50.758759099902 | 2004 | 50.766403899615 | 2003 | 50.77387223446 | 2002 | 50.7803167508 | 2001 | 50.796434454026 | 2000 | 50.819176827188 | 1999 | 50.841324939695 | 1998 | 50.86389785185 | 1997 | 50.893123249021 | 1996 | 50.895753281102 | 1995 | 50.86369865069 | 1994 | 50.834745465302 | 1993 | 50.796043903027 | 1992 | 50.745516824501 | 1991 | 50.692859307141 | 1990 | 50.643694227516 | 1989 | 50.600229723823 | 1988 | 50.565147693973 | 1987 | 50.538031871201 | 1986 | 50.558313933126 | 1985 | 50.629024779764 | 1984 | 50.703964049391 | 1983 | 50.782111960075 | 1982 | 50.860921686561 | 1981 | 50.934473287487 | 1980 | 51.006121520453 | 1979 | 51.075580792904 | 1978 | 51.146767539256 | 1977 | 51.219130489217 | 1976 | 51.259468400038 | 1975 | 51.25752858992 | 1974 | 51.252622083102 | 1973 | 51.271920627738 | 1972 | 51.318958274993 | 1971 | 51.365125591554 | 1970 | 51.407196706905 | 1969 | 51.450051178277 | 1968 | 51.494666187223 | 1967 | 51.532578770266 | 1966 | 51.52267087751 | 1965 | 51.479030970831 | 1964 | 51.438896537118 | 1963 | 51.397720619273 | 1962 | 51.35737098672 | 1961 | 51.309247596951 | 1960 | 51.260603903423 |
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