| Year | Value | | 2022 | 0.11460107844368 | | 2021 | 0.23071274806506 | | 2020 | 0.36554733008511 | | 2019 | 0.38993403705453 | | 2018 | 0.40839260143256 | | 2017 | 0.4242375754345 | | 2016 | 0.44881848795765 | | 2015 | 0.46743058680006 | | 2014 | 0.47364918156948 | | 2013 | 0.49207536874806 | | 2012 | 0.56709558268908 | | 2011 | 0.70537776439133 | | 2010 | 0.73219105639163 | | 2009 | 0.6574770036154 | | 2008 | 0.62958785027738 | | 2007 | 0.62756951720679 | | 2006 | 0.65329772877703 | | 2005 | 0.6959451676762 | | 2004 | 0.72841812393572 | | 2003 | 0.76836786664538 | | 2002 | 0.74753832211872 | | 2001 | 0.683551868949 | | 2000 | 0.78299472274143 | | 1999 | 0.8892163278823 | | 1998 | 0.89719437984125 | | 1997 | 0.95985844712218 | | 1996 | 1.0583905770035 | | 1995 | 1.1799059993629 | | 1994 | 1.3143833343295 | | 1993 | 1.4745280123572 | | 1992 | 1.4806523252865 | | 1991 | 1.372814848763 | | 1990 | 1.3043140369069 | | 1989 | 1.2876498594587 | | 1988 | 1.3651097844394 | | 1987 | 1.4507415966977 | | 1986 | 1.5391186652611 | | 1985 | 1.6144570331286 | | 1984 | 1.6868753497762 | | 1983 | 1.7641463826049 | | 1982 | 1.8272980173087 | | 1981 | 1.8539110928483 | | 1980 | 1.8001614296322 | | 1979 | 1.7445346592568 | | 1978 | 1.7286990448262 | | 1977 | 1.7167803622366 | | 1976 | 1.7108874625568 | | 1975 | 1.5883753077779 | | 1974 | 1.4927705658097 | | 1973 | 1.5445078223144 | | 1972 | 1.5868690008986 | | 1971 | 1.6270064632308 | | 1970 | 1.4509646576387 | | 1969 | 1.1930539274278 | | 1968 | 1.1449761210125 | | 1967 | 1.1460078914057 | | 1966 | 1.1293996553595 | | 1965 | 1.1151992533068 | | 1964 | 1.1119668115752 | | 1963 | 1.1276681417452 | | 1962 | 1.1383735675519 | | 1961 | 1.2442194408632 |
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