Year | Value | 2022 | 49.507459532256 | 2021 | 49.517653186574 | 2020 | 49.540768291472 | 2019 | 49.560551071336 | 2018 | 49.565177482609 | 2017 | 49.56754976019 | 2016 | 49.555778493144 | 2015 | 49.543282346629 | 2014 | 49.55434631887 | 2013 | 49.585421312809 | 2012 | 49.632399963576 | 2011 | 49.690907244831 | 2010 | 49.762901078401 | 2009 | 49.849786237708 | 2008 | 49.947696996322 | 2007 | 49.987788626776 | 2006 | 49.965547467929 | 2005 | 49.942987360016 | 2004 | 49.921565319399 | 2003 | 49.902030315594 | 2002 | 49.884781150036 | 2001 | 49.870961993616 | 2000 | 49.86173972748 | 1999 | 49.857092189356 | 1998 | 49.856090035001 | 1997 | 49.856722069989 | 1996 | 49.857049964139 | 1995 | 49.856131453752 | 1994 | 49.853668755096 | 1993 | 49.855680997293 | 1992 | 49.863957727187 | 1991 | 49.87273173465 | 1990 | 49.882068916513 | 1989 | 49.89405674012 | 1988 | 49.90768688257 | 1987 | 49.922109624137 | 1986 | 49.938231244702 | 1985 | 49.956382386648 | 1984 | 49.979015481255 | 1983 | 50.002353015413 | 1982 | 50.020517708034 | 1981 | 50.034507479892 | 1980 | 50.045265356864 | 1979 | 50.063804337663 | 1978 | 50.092544511278 | 1977 | 50.121873477044 | 1976 | 50.159593090536 | 1975 | 50.203616916158 | 1974 | 50.244830122516 | 1973 | 50.283142138028 | 1972 | 50.303842514751 | 1971 | 50.307706285696 | 1970 | 50.298476571685 | 1969 | 50.287537842241 | 1968 | 50.286777123141 | 1967 | 50.285683932526 | 1966 | 50.284160854354 | 1965 | 50.282954384475 | 1964 | 50.282237812132 | 1963 | 50.281746097808 | 1962 | 50.281826677937 | 1961 | 50.28118658199 | 1960 | 50.279560767884 |
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