Year | Value | 2022 | 49.732840475106 | 2021 | 49.706092936507 | 2020 | 49.679767363031 | 2019 | 49.656577990465 | 2018 | 49.638056775054 | 2017 | 49.624196323463 | 2016 | 49.613827609734 | 2015 | 49.601688257112 | 2014 | 49.591832990901 | 2013 | 49.586130062886 | 2012 | 49.582378594131 | 2011 | 49.578725889125 | 2010 | 49.578949325204 | 2009 | 49.573552860904 | 2008 | 49.563033559023 | 2007 | 49.55538107585 | 2006 | 49.541708597383 | 2005 | 49.525869839553 | 2004 | 49.526193937436 | 2003 | 49.536246142838 | 2002 | 49.553539538539 | 2001 | 49.579268946297 | 2000 | 49.592244134313 | 1999 | 49.544105649145 | 1998 | 49.433603217062 | 1997 | 49.318384278297 | 1996 | 49.220562350499 | 1995 | 49.131680081212 | 1994 | 49.094116350005 | 1993 | 49.148354239366 | 1992 | 49.24533252991 | 1991 | 49.299491172693 | 1990 | 49.303773718852 | 1989 | 49.306789536758 | 1988 | 49.309905566025 | 1987 | 49.309063492918 | 1986 | 49.303627332766 | 1985 | 49.29972944092 | 1984 | 49.292168850753 | 1983 | 49.286255456808 | 1982 | 49.278608196397 | 1981 | 49.267168379366 | 1980 | 49.257526310961 | 1979 | 49.247105809968 | 1978 | 49.231068446717 | 1977 | 49.190237226277 | 1976 | 49.122474563424 | 1975 | 49.05320242547 | 1974 | 49.009946302172 | 1973 | 48.999045219052 | 1972 | 48.993816750984 | 1971 | 48.98719364462 | 1970 | 48.975232670498 | 1969 | 48.960444475505 | 1968 | 48.951451766781 | 1967 | 48.939562476826 | 1966 | 48.920643411149 | 1965 | 48.90561279773 | 1964 | 48.891958318945 | 1963 | 48.869299384396 | 1962 | 48.861471861472 | 1961 | 48.870138904472 | 1960 | 48.874052016936 |
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