Year | Value | 2021 | 28.747820020928 | 2020 | 28.747820020928 | 2019 | 28.747820020928 | 2018 | 28.747820020928 | 2017 | 28.747820020928 | 2016 | 28.747820020928 | 2015 | 28.747820020928 | 2014 | 28.747820020928 | 2013 | 28.747820020928 | 2012 | 28.747820020928 | 2011 | 28.786885245902 | 2010 | 28.782699686083 | 2009 | 28.880362748518 | 2008 | 28.96407394489 | 2007 | 29.061737007325 | 2006 | 29.194279734914 | 2005 | 29.312870596442 | 2004 | 29.424485524939 | 2003 | 29.487268922218 | 2002 | 29.584931984653 | 2001 | 29.710498779212 | 2000 | 29.641437042204 | 1999 | 29.626573426573 | 1998 | 29.548251748252 | 1997 | 29.46993006993 | 1996 | 29.391608391608 | 1995 | 29.313286713287 | 1994 | 29.234965034965 | 1993 | 29.156643356643 | 1992 | 29.078321678322 | 1991 | 29 | 1990 | 28.981818181818 | 1989 | 28.956643356643 | 1988 | 28.938461538461 | 1987 | 28.913286713287 | 1986 | 28.895104895105 | 1985 | 28.786013986014 | 1984 | 28.767832167832 | 1983 | 28.742657342657 | 1982 | 28.717482517483 | 1981 | 28.692307692308 | 1980 | 28.566433566434 | 1979 | 28.461538461538 | 1978 | 28.356643356643 | 1977 | 28.251748251748 | 1976 | 28.146853146853 | 1975 | 28.034965034965 | 1974 | 27.93006993007 | 1973 | 27.643356643357 | 1972 | 26.727272727273 | 1971 | 25.888111888112 | 1970 | 25.888111888112 | 1969 | 24.944055944056 | 1968 | 24.944055944056 | 1967 | 24.944055944056 | 1966 | 24.846153846154 | 1965 | 24.846153846154 | 1964 | 24.846153846154 | 1963 | 24.916083916084 | 1962 | 24.846153846154 | 1961 | 24.846153846154 |
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