Year | Value | 2021 | 34.198106222384 | 2020 | 34.092751776734 | 2019 | 33.83925761443 | 2018 | 33.58523428679 | 2017 | 33.263928222695 | 2016 | 33.079366025142 | 2015 | 32.892960180184 | 2014 | 32.706023879481 | 2013 | 32.518083417923 | 2012 | 32.330835764456 | 2011 | 32.186782479327 | 2010 | 31.617861452808 | 2009 | 30.998892907568 | 2008 | 30.581221414958 | 2007 | 31.079243939183 | 2006 | 30.319510141553 | 2005 | 29.763429881838 | 2004 | 29.32932773097 | 2003 | 31.607 | 2002 | 30.498 | 2001 | 30.559 | 2000 | 30.534 | 1999 | 30.557 | 1998 | 30.449 | 1997 | 30.492 | 1996 | 30.5 | 1995 | 30.5 | 1994 | 30.472 | 1993 | 30.54 | 1992 | 50.958219800182 | 1991 | 51.006357856494 | 1990 | 51.146230699364 | 1989 | 51.33514986376 | 1988 | 51.566757493188 | 1987 | 51.798365122616 | 1986 | 52.120799273388 | 1985 | 52.397820163488 | 1984 | 52.579473206176 | 1983 | 52.995458673933 | 1982 | 53.228882833788 | 1981 | 53.460490463215 | 1980 | 53.692098092643 | 1979 | 53.839237057221 | 1978 | 53.850136239782 | 1977 | 53.869209809264 | 1976 | 53.887375113533 | 1975 | 53.932788374205 | 1974 | 53.978201634877 | 1973 | 54.023614895549 | 1972 | 54.069028156222 | 1971 | 53.896457765668 | 1970 | 53.723887375113 | 1969 | 53.769300635786 | 1968 | 53.560399636694 | 1967 | 53.451407811081 | 1966 | 53.378746594005 | 1965 | 53.292461398728 | 1964 | 52.979109900091 | 1963 | 53.024523160763 | 1962 | 52.905540417802 | 1961 | 52.53042688465 |
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