Year | Value | 2022 | 49.659709520313 | 2021 | 49.650866414266 | 2020 | 49.64391414333 | 2019 | 49.636702412277 | 2018 | 49.62478700953 | 2017 | 49.610908178525 | 2016 | 49.598301509255 | 2015 | 49.591652879218 | 2014 | 49.581173278902 | 2013 | 49.559464399354 | 2012 | 49.53503549954 | 2011 | 49.509181361191 | 2010 | 49.482069181256 | 2009 | 49.449408831825 | 2008 | 49.416865615082 | 2007 | 49.387188217822 | 2006 | 49.357367733107 | 2005 | 49.329952033287 | 2004 | 49.301326761507 | 2003 | 49.272699022832 | 2002 | 49.251534605978 | 2001 | 49.239397444588 | 2000 | 49.233495342725 | 1999 | 49.224423884094 | 1998 | 49.208081069169 | 1997 | 49.197111614011 | 1996 | 49.205860477022 | 1995 | 49.216177298243 | 1994 | 49.164722662577 | 1993 | 49.174002109727 | 1992 | 49.21671888889 | 1991 | 49.191056454282 | 1990 | 49.177494482377 | 1989 | 49.165630291399 | 1988 | 49.167046040851 | 1987 | 49.164532184361 | 1986 | 49.143504202744 | 1985 | 49.122336512515 | 1984 | 49.09596081836 | 1983 | 49.064509809149 | 1982 | 49.029381364113 | 1981 | 48.997682566114 | 1980 | 48.949275580743 | 1979 | 48.8968412087 | 1978 | 48.861789221693 | 1977 | 48.820322103932 | 1976 | 48.779982923024 | 1975 | 48.738728358234 | 1974 | 48.691978649367 | 1973 | 48.66032003808 | 1972 | 48.733779523049 | 1971 | 48.792262574433 | 1970 | 48.75357149596 | 1969 | 48.720005583413 | 1968 | 48.686238533205 | 1967 | 48.64692030186 | 1966 | 48.60361034616 | 1965 | 48.569048026801 | 1964 | 48.528544408733 | 1963 | 48.474983998347 | 1962 | 48.430870977953 | 1961 | 48.380239576246 | 1960 | 48.331226507558 |
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