Year | Value | 2022 | 49.178922306762 | 2021 | 49.162734227978 | 2020 | 49.141318023962 | 2019 | 49.126464514451 | 2018 | 49.115882474819 | 2017 | 49.104965346868 | 2016 | 49.097981229658 | 2015 | 49.095863307937 | 2014 | 49.098087171736 | 2013 | 49.109261063497 | 2012 | 49.125967656938 | 2011 | 49.140680093322 | 2010 | 49.155271525311 | 2009 | 49.169632970943 | 2008 | 49.183861876037 | 2007 | 49.19798036453 | 2006 | 49.211662530995 | 2005 | 49.224949351001 | 2004 | 49.239098502798 | 2003 | 49.256370978438 | 2002 | 49.275057828592 | 2001 | 49.296636042547 | 2000 | 49.325303342739 | 1999 | 49.360863101204 | 1998 | 49.406577274631 | 1997 | 49.461312601095 | 1996 | 49.51557784808 | 1995 | 49.562262291402 | 1994 | 49.598841487053 | 1993 | 49.627044350728 | 1992 | 49.652844047926 | 1991 | 49.680273716907 | 1990 | 49.711471641259 | 1989 | 49.745842297392 | 1988 | 49.781490084677 | 1987 | 49.816529680801 | 1986 | 49.852560429809 | 1985 | 49.897748786366 | 1984 | 49.958221647132 | 1983 | 50.029180764222 | 1982 | 50.104753484793 | 1981 | 50.188062977815 | 1980 | 50.281729822336 | 1979 | 50.385499150504 | 1978 | 50.498626506357 | 1977 | 50.616026194465 | 1976 | 50.710116102559 | 1975 | 50.764334314199 | 1974 | 50.784345304546 | 1973 | 50.771881788896 | 1972 | 50.738909132975 | 1971 | 50.695636168991 | 1970 | 50.643352723969 | 1969 | 50.580460232231 | 1968 | 50.509209237579 | 1967 | 50.433343363677 | 1966 | 50.356028370987 | 1965 | 50.279006935793 | 1964 | 50.205274847262 | 1963 | 50.136099429918 | 1962 | 50.064327546164 | 1961 | 49.988922158712 | 1960 | 49.911385788181 |
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