Year | Value | 2022 | 50.935843223428 | 2021 | 50.939340722869 | 2020 | 50.948804388856 | 2019 | 50.960887511043 | 2018 | 50.968784604123 | 2017 | 50.988057484219 | 2016 | 51.036324346191 | 2015 | 51.0926212128 | 2014 | 51.139081269175 | 2013 | 51.187354245141 | 2012 | 51.23360951789 | 2011 | 51.273847378378 | 2010 | 51.302956180934 | 2009 | 51.314241959365 | 2008 | 51.311714397394 | 2007 | 51.31275735693 | 2006 | 51.318712564469 | 2005 | 51.320624879955 | 2004 | 51.323489694614 | 2003 | 51.324846297607 | 2002 | 51.318976797259 | 2001 | 51.307056210085 | 2000 | 51.285057465442 | 1999 | 51.25345392315 | 1998 | 51.220215804403 | 1997 | 51.186788981586 | 1996 | 51.179289623287 | 1995 | 51.200250339375 | 1994 | 51.222510913893 | 1993 | 51.245324770344 | 1992 | 51.264275924501 | 1991 | 51.280836653166 | 1990 | 51.297854189651 | 1989 | 51.315145232084 | 1988 | 51.331489046809 | 1987 | 51.301898919636 | 1986 | 51.229628165338 | 1985 | 51.156985394002 | 1984 | 51.081032426346 | 1983 | 51.046752993918 | 1982 | 51.055623645009 | 1981 | 51.064470277744 | 1980 | 51.077343170031 | 1979 | 51.042475074237 | 1978 | 50.942731526894 | 1977 | 50.828927276543 | 1976 | 50.734898260442 | 1975 | 50.6605396769 | 1974 | 50.583264685081 | 1973 | 50.502473347342 | 1972 | 50.423623270924 | 1971 | 50.374874317079 | 1970 | 50.367786395957 | 1969 | 50.39149761558 | 1968 | 50.43507403184 | 1967 | 50.486018715509 | 1966 | 50.546221716665 | 1965 | 50.613849743107 | 1964 | 50.691580616595 | 1963 | 50.790804802403 | 1962 | 50.904965967818 | 1961 | 51.028540426549 | 1960 | 51.09586609461 |
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