Year | Value | 2023 | 49.000538562562 | 2022 | 48.971608803392 | 2021 | 48.937496989312 | 2020 | 48.91372094919 | 2019 | 48.887060202414 | 2018 | 48.815437780789 | 2017 | 48.69424304076 | 2016 | 48.549039421476 | 2015 | 48.439235710587 | 2014 | 48.373099835139 | 2013 | 48.300362494922 | 2012 | 48.222239760755 | 2011 | 48.144530933488 | 2010 | 48.070199030267 | 2009 | 47.996896423381 | 2008 | 47.912411537579 | 2007 | 47.812243155883 | 2006 | 47.707779938425 | 2005 | 47.600947698502 | 2004 | 47.495616542719 | 2003 | 47.401675846643 | 2002 | 47.315158189282 | 2001 | 47.224080745818 | 2000 | 47.132909305872 | 1999 | 47.054572505722 | 1998 | 47.137937474917 | 1997 | 47.366744529072 | 1996 | 47.587007606453 | 1995 | 47.812859772821 | 1994 | 48.056096990719 | 1993 | 48.171243134099 | 1992 | 48.151632913751 | 1991 | 48.123103374919 | 1990 | 48.079912311805 | 1989 | 48.036319067022 | 1988 | 47.979228983623 | 1987 | 47.998819661098 | 1986 | 48.102838515774 | 1985 | 48.196774205883 | 1984 | 48.281543824364 | 1983 | 48.285043786084 | 1982 | 48.213130070624 | 1981 | 48.142227422809 | 1980 | 48.074397103954 | 1979 | 48.009934809881 | 1978 | 48.040576275823 | 1977 | 48.154081419554 | 1976 | 48.242880684146 | 1975 | 48.260892649286 | 1974 | 48.2188260917 |
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