Year | Value | 2022 | 52.237892210428 | 2021 | 52.188004098984 | 2020 | 52.147631688361 | 2019 | 52.111568950729 | 2018 | 52.064413071713 | 2017 | 52.009673700566 | 2016 | 51.956684243489 | 2015 | 51.90872351966 | 2014 | 51.864539191172 | 2013 | 51.819784778945 | 2012 | 51.774454864537 | 2011 | 51.725625082683 | 2010 | 51.660451359866 | 2009 | 51.59608430216 | 2008 | 51.535991400102 | 2007 | 51.469807026667 | 2006 | 51.409273416056 | 2005 | 51.358811284517 | 2004 | 51.312050226035 | 2003 | 51.261780259387 | 2002 | 51.213166388225 | 2001 | 51.167687014981 | 2000 | 51.116567286332 | 1999 | 51.072213618424 | 1998 | 51.042175283293 | 1997 | 51.008959573912 | 1996 | 50.975460183057 | 1995 | 50.944070184341 | 1994 | 50.914805253115 | 1993 | 50.886994905679 | 1992 | 50.861607317013 | 1991 | 50.828449094031 | 1990 | 50.840294223046 | 1989 | 50.832978647271 | 1988 | 50.74293919801 | 1987 | 50.631019724745 | 1986 | 50.502783049712 | 1985 | 50.379165226584 | 1984 | 50.262474809882 | 1983 | 50.147937747796 | 1982 | 50.026919117742 | 1981 | 49.899103335732 | 1980 | 49.832403732704 | 1979 | 49.833656904833 | 1978 | 49.841872232764 | 1977 | 49.857980183723 | 1976 | 49.875300830681 | 1975 | 49.883842461648 | 1974 | 49.879909186062 | 1973 | 49.871101398511 | 1972 | 49.867058531248 | 1971 | 49.891289614227 | 1970 | 49.973482797314 | 1969 | 50.047179368433 | 1968 | 50.069504883474 | 1967 | 50.088813315044 | 1966 | 50.11663792021 | 1965 | 50.151537117964 | 1964 | 50.179774471304 | 1963 | 50.319287690649 | 1962 | 50.594196587625 | 1961 | 50.890064550476 | 1960 | 51.196506550218 |
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