Year | Value | 2022 | 48.161786041801 | 2021 | 48.178393116642 | 2020 | 48.197784590146 | 2019 | 48.226429749672 | 2018 | 48.255757109011 | 2017 | 48.287972746125 | 2016 | 48.324127322338 | 2015 | 48.36227462948 | 2014 | 48.402687507501 | 2013 | 48.448179129079 | 2012 | 48.496239760801 | 2011 | 48.56820143949 | 2010 | 48.671893253119 | 2009 | 48.789938834058 | 2008 | 48.912080331888 | 2007 | 49.028234211903 | 2006 | 49.139371293602 | 2005 | 49.243722611509 | 2004 | 49.345907230066 | 2003 | 49.454198738239 | 2002 | 49.568453956204 | 2001 | 49.685826448083 | 2000 | 49.777100164883 | 1999 | 49.839588426843 | 1998 | 49.906394110857 | 1997 | 49.978879754881 | 1996 | 50.050435240682 | 1995 | 50.121770938385 | 1994 | 50.189032222532 | 1993 | 50.249643616704 | 1992 | 50.312279124401 | 1991 | 50.383783375351 | 1990 | 50.458466455717 | 1989 | 50.539390220755 | 1988 | 50.620267303599 | 1987 | 50.690098149293 | 1986 | 50.753759882878 | 1985 | 50.812604110105 | 1984 | 50.869653995063 | 1983 | 50.924415085485 | 1982 | 50.977485033927 | 1981 | 51.031264199202 | 1980 | 51.086973760418 | 1979 | 51.144598572231 | 1978 | 51.19998063104 | 1977 | 51.254942774417 | 1976 | 51.313700695247 | 1975 | 51.374641336416 | 1974 | 51.437524462904 | 1973 | 51.5019851953 | 1972 | 51.568261832456 | 1971 | 51.636019041537 | 1970 | 51.709060036554 | 1969 | 51.794197425624 | 1968 | 51.887963136083 | 1967 | 51.985591920773 | 1966 | 52.085330248419 | 1965 | 52.186407815555 | 1964 | 52.290022559686 | 1963 | 52.395937791864 | 1962 | 52.504556559337 | 1961 | 52.617558931118 | 1960 | 52.736733752929 |
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