Year | Value | 2022 | 51.454370820663 | 2021 | 51.464284834913 | 2020 | 51.465801902422 | 2019 | 51.473429001066 | 2018 | 51.488294241953 | 2017 | 51.50722521677 | 2016 | 51.527371249257 | 2015 | 51.549607335118 | 2014 | 51.57168956169 | 2013 | 51.592413626801 | 2012 | 51.613834301955 | 2011 | 51.634525583936 | 2010 | 51.652220589795 | 2009 | 51.667930746982 | 2008 | 51.68149517155 | 2007 | 51.695221804254 | 2006 | 51.704073709869 | 2005 | 51.707433302485 | 2004 | 51.709215445629 | 2003 | 51.710803240956 | 2002 | 51.712276611283 | 2001 | 51.710960803885 | 2000 | 51.709307166363 | 1999 | 51.708876715286 | 1998 | 51.706291044534 | 1997 | 51.703682062276 | 1996 | 51.700193477094 | 1995 | 51.695037494523 | 1994 | 51.690485275377 | 1993 | 51.690509204286 | 1992 | 51.696103823456 | 1991 | 51.708023595749 | 1990 | 51.725675790219 | 1989 | 51.749353199229 | 1988 | 51.77405387774 | 1987 | 51.797870831887 | 1986 | 51.822006234709 | 1985 | 51.84406087939 | 1984 | 51.863906139858 | 1983 | 51.883971782972 | 1982 | 51.905031261888 | 1981 | 51.925199084807 | 1980 | 51.948730562794 | 1979 | 51.969209289542 | 1978 | 51.98343206914 | 1977 | 52.000659183724 | 1976 | 52.017161574215 | 1975 | 52.037788718537 | 1974 | 52.069093983289 | 1973 | 52.103754595318 | 1972 | 52.139144277571 | 1971 | 52.17599755286 | 1970 | 52.191604841898 | 1969 | 52.200528092826 | 1968 | 52.226842980586 | 1967 | 52.257450774949 | 1966 | 52.29210485566 | 1965 | 52.331890768815 | 1964 | 52.374995045071 | 1963 | 52.422843893445 | 1962 | 52.474451201131 | 1961 | 52.527481005019 | 1960 | 52.581726493276 |
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