Year | Value | 2023 | 51.577576935104 | 2022 | 51.594294326936 | 2021 | 51.614243512231 | 2020 | 51.633063214281 | 2019 | 51.646217455773 | 2018 | 51.654311344665 | 2017 | 51.660768036123 | 2016 | 51.666266508199 | 2015 | 51.671367474831 | 2014 | 51.677273746692 | 2013 | 51.685098846469 | 2012 | 51.694471882168 | 2011 | 51.704312447451 | 2010 | 51.713605159356 | 2009 | 51.722101209885 | 2008 | 51.729842952752 | 2007 | 51.736615680103 | 2006 | 51.742148980902 | 2005 | 51.745854289575 | 2004 | 51.747662806454 | 2003 | 51.74766558086 | 2002 | 51.746164601438 | 2001 | 51.742945836444 | 2000 | 51.73708555459 | 1999 | 51.729392798282 | 1998 | 51.720141985873 | 1997 | 51.709607972175 | 1996 | 51.699264736693 | 1995 | 51.689645664829 | 1994 | 51.682541634665 | 1993 | 51.67974369447 | 1992 | 51.681303196892 | 1991 | 51.686568765479 | 1990 | 51.695437968151 | 1989 | 51.707129360974 | 1988 | 51.718728363228 | 1987 | 51.728844271651 | 1986 | 51.738632752799 | 1985 | 51.748864779255 | 1984 | 51.758815597985 | 1983 | 51.768373098374 | 1982 | 51.777060971996 | 1981 | 51.783664556136 | 1980 | 51.788264480644 | 1979 | 51.79114370096 | 1978 | 51.791431120725 | 1977 | 51.788210526564 | 1976 | 51.780818921287 | 1975 | 51.770395144828 | 1974 | 51.758684836984 |
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