Year | Value | 2022 | 46.073323527664 | 2021 | 46.121369341943 | 2020 | 46.156584265637 | 2019 | 46.182225956301 | 2018 | 46.198711364148 | 2017 | 46.213070019657 | 2016 | 46.220397268559 | 2015 | 46.297243263974 | 2014 | 46.447320476109 | 2013 | 46.595266682354 | 2012 | 46.734516993224 | 2011 | 46.884673725263 | 2010 | 47.07224934868 | 2009 | 47.275651393772 | 2008 | 47.473923426077 | 2007 | 47.67025601532 | 2006 | 47.877760450077 | 2005 | 48.108081536438 | 2004 | 48.351069505804 | 2003 | 48.594654696893 | 2002 | 48.83624937161 | 2001 | 49.071357642135 | 2000 | 49.284309843943 | 1999 | 49.481275496032 | 1998 | 49.680700916598 | 1997 | 49.88424581866 | 1996 | 50.083145915556 | 1995 | 50.236880749549 | 1994 | 50.35888396061 | 1993 | 50.486452118031 | 1992 | 50.619414965998 | 1991 | 50.759329829405 | 1990 | 50.899380567926 | 1989 | 51.043734533371 | 1988 | 51.196065671223 | 1987 | 51.354056702721 | 1986 | 51.512755537212 | 1985 | 51.662736895012 | 1984 | 51.807110095656 | 1983 | 51.965917808157 | 1982 | 52.142104412603 | 1981 | 52.296453817465 | 1980 | 52.290790239074 | 1979 | 52.151309978427 | 1978 | 52.013589168591 | 1977 | 51.873918921787 | 1976 | 51.728288987212 | 1975 | 51.577792155858 | 1974 | 51.427924047607 | 1973 | 51.279484003085 | 1972 | 51.128724354358 | 1971 | 50.993482855728 | 1970 | 50.960412351532 | 1969 | 51.012482855088 | 1968 | 51.063042328946 | 1967 | 51.114899697702 | 1966 | 51.171354790734 | 1965 | 51.233790732945 | 1964 | 51.303003929426 | 1963 | 51.375807342292 | 1962 | 51.448672365534 | 1961 | 51.51425323307 | 1960 | 51.542843529862 |
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