| Year | Value | | 2024 | 49.657154834266 | | 2023 | 49.659083830512 | | 2022 | 49.669577958057 | | 2021 | 49.683645855199 | | 2020 | 49.681696491878 | | 2019 | 49.668518340357 | | 2018 | 49.644527464201 | | 2017 | 49.617864049162 | | 2016 | 49.603841121191 | | 2015 | 49.601092635124 | | 2014 | 49.600708733614 | | 2013 | 49.591622328154 | | 2012 | 49.57239907915 | | 2011 | 49.553710090271 | | 2010 | 49.545463171968 | | 2009 | 49.54489648165 | | 2008 | 49.545615373335 | | 2007 | 49.548906900064 | | 2006 | 49.551998736476 | | 2005 | 49.548101978371 | | 2004 | 49.540936162897 | | 2003 | 49.536798695283 | | 2002 | 49.531852563476 | | 2001 | 49.517738691651 | | 2000 | 49.495498854502 | | 1999 | 49.479361642225 | | 1998 | 49.478547109626 | | 1997 | 49.478438950695 | | 1996 | 49.470919422902 | | 1995 | 49.474451589409 | | 1994 | 49.489101610879 | | 1993 | 49.504896475232 | | 1992 | 49.532699229405 | | 1991 | 49.556205210767 | | 1990 | 49.558285481227 | | 1989 | 49.569309418056 | | 1988 | 49.594677558747 | | 1987 | 49.612277946657 | | 1986 | 49.619845171295 | | 1985 | 49.63403288235 | | 1984 | 49.662671464675 | | 1983 | 49.697992429585 | | 1982 | 49.733518047058 | | 1981 | 49.767266802826 | | 1980 | 49.800238658737 | | 1979 | 49.836301033801 | | 1978 | 49.88345300393 | | 1977 | 49.93952889002 | | 1976 | 49.995779291927 |
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