Year | Value | 2022 | 48.412594419646 | 2021 | 48.360052935659 | 2020 | 48.311270980262 | 2019 | 48.265431041764 | 2018 | 48.223266515007 | 2017 | 48.183360329732 | 2016 | 48.142517576641 | 2015 | 48.100821291994 | 2014 | 48.062056534186 | 2013 | 48.026572145454 | 2012 | 47.992741584331 | 2011 | 47.962022571307 | 2010 | 47.939523179252 | 2009 | 47.9230427415 | 2008 | 47.906735063158 | 2007 | 47.894630682614 | 2006 | 47.884914873803 | 2005 | 47.872197682717 | 2004 | 47.856198295103 | 2003 | 47.839707239229 | 2002 | 47.823981145152 | 2001 | 47.808638395196 | 2000 | 47.771988329605 | 1999 | 47.710165092265 | 1998 | 47.644064435691 | 1997 | 47.573450656283 | 1996 | 47.497113914952 | 1995 | 47.415876176421 | 1994 | 47.330027625439 | 1993 | 47.239227064667 | 1992 | 47.142877172897 | 1991 | 47.041827915094 | 1990 | 46.934440922211 | 1989 | 46.869301444803 | 1988 | 46.867596954168 | 1987 | 46.881366580906 | 1986 | 46.896207573499 | 1985 | 46.914602972115 | 1984 | 46.937870151268 | 1983 | 46.965911013698 | 1982 | 46.999132064648 | 1981 | 47.037666850842 | 1980 | 47.057512461398 | 1979 | 47.05559219199 | 1978 | 47.0536037315 | 1977 | 47.051555197267 | 1976 | 47.049393925494 | 1975 | 47.046372432332 | 1974 | 47.041447503451 | 1973 | 47.0335805256 | 1972 | 47.020032941357 | 1971 | 47.014786324954 | 1970 | 47.023955639461 | 1969 | 47.036515363307 | 1968 | 47.051726141261 | 1967 | 47.070734381936 | 1966 | 47.087330342639 | 1965 | 47.103157352831 | 1964 | 47.122495126204 | 1963 | 47.134634152756 | 1962 | 47.130121456168 | 1961 | 47.108571518398 | 1960 | 47.05076281711 |
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