| Year | Value | | 2021 | 43.064596895343 | | 2020 | 43.064596895343 | | 2019 | 43.064596895343 | | 2018 | 43.064596895343 | | 2017 | 43.064596895343 | | 2016 | 43.064596895343 | | 2015 | 43.064596895343 | | 2014 | 43.064596895343 | | 2013 | 43.064596895343 | | 2012 | 43.565348022033 | | 2011 | 44.566850275413 | | 2010 | 44.827586206897 | | 2009 | 44.827586206897 | | 2008 | 44.827586206897 | | 2007 | 45.320197044335 | | 2006 | 46.305418719212 | | 2005 | 47.290640394089 | | 2004 | 48.275862068966 | | 2003 | 48.768472906404 | | 2002 | 49.261083743842 | | 2001 | 50.246305418719 | | 2000 | 49.753694581281 | | 1999 | 49.261083743842 | | 1998 | 50.246305418719 | | 1997 | 50.246305418719 | | 1996 | 50.738916256158 | | 1995 | 51.231527093596 | | 1994 | 51.724137931034 | | 1993 | 52.709359605911 | | 1992 | 53.694581280788 | | 1991 | 54.187192118227 | | 1990 | 54.679802955665 | | 1989 | 55.172413793103 | | 1988 | 55.665024630542 | | 1987 | 56.15763546798 | | 1986 | 56.15763546798 | | 1985 | 56.15763546798 | | 1984 | 56.15763546798 | | 1983 | 56.15763546798 | | 1982 | 56.15763546798 | | 1981 | 56.15763546798 | | 1980 | 56.15763546798 | | 1979 | 56.15763546798 | | 1978 | 56.15763546798 | | 1977 | 56.15763546798 | | 1976 | 56.15763546798 | | 1975 | 55.665024630542 | | 1974 | 55.665024630542 | | 1973 | 55.665024630542 | | 1972 | 55.665024630542 | | 1971 | 55.172413793103 | | 1970 | 55.172413793103 | | 1969 | 54.679802955665 | | 1968 | 54.679802955665 | | 1967 | 51.724137931034 | | 1966 | 48.768472906404 | | 1965 | 49.753694581281 | | 1964 | 49.261083743842 | | 1963 | 49.261083743842 | | 1962 | 49.261083743842 | | 1961 | 48.768472906404 |
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