Year | Value | 2022 | 50.658317366723 | 2021 | 50.652264638623 | 2020 | 50.629993278529 | 2019 | 50.637966146549 | 2018 | 50.668415197721 | 2017 | 50.695070588321 | 2016 | 50.720441191919 | 2015 | 50.752766771971 | 2014 | 50.79556512706 | 2013 | 50.843540335731 | 2012 | 50.89285036565 | 2011 | 50.944169973461 | 2010 | 50.997932057781 | 2009 | 51.050755579065 | 2008 | 51.138449565407 | 2007 | 51.261999472653 | 2006 | 51.383916635562 | 2005 | 51.504400815273 | 2004 | 51.6230287311 | 2003 | 51.717188261094 | 2002 | 51.788404547614 | 2001 | 51.859600003526 | 2000 | 51.929694712196 | 1999 | 51.987699978115 | 1998 | 51.975812749904 | 1997 | 51.906366713954 | 1996 | 51.836037811068 | 1995 | 51.763280278553 | 1994 | 51.69161378083 | 1993 | 51.667464028598 | 1992 | 51.688254529631 | 1991 | 51.719221407255 | 1990 | 51.765480551805 | 1989 | 51.812645039226 | 1988 | 51.865551343031 | 1987 | 51.901058297121 | 1986 | 51.91023076055 | 1985 | 51.919754931695 | 1984 | 51.924644673889 | 1983 | 51.91963361262 | 1982 | 51.905239144993 | 1981 | 51.885385052261 | 1980 | 51.860815972277 | 1979 | 51.835527744994 | 1978 | 51.773577964629 | 1977 | 51.66773358318 | 1976 | 51.565537060189 | 1975 | 51.539693084166 | 1974 | 51.580560372227 | 1973 | 51.622245514757 | 1972 | 51.666043850962 | 1971 | 51.710470083345 | 1970 | 51.758210626218 | 1969 | 51.810194081656 | 1968 | 51.864350406353 | 1967 | 51.922730213271 | 1966 | 51.989544136759 | 1965 | 52.062224009991 | 1964 | 52.141441415563 | 1963 | 52.2302139643 | 1962 | 52.32632930189 | 1961 | 52.428847046502 | 1960 | 52.535093927509 |
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