| Year | Value | | 2022 | 0.56551412797416 | | 2021 | 0.99434489841826 | | 2020 | 1.3606436343094 | | 2019 | 1.7913919716665 | | 2018 | 1.795962799012 | | 2017 | 1.5620554558887 | | 2016 | 1.1890610261228 | | 2015 | 1.0294255537485 | | 2014 | 1.0068149591811 | | 2013 | 0.96497630900934 | | 2012 | 0.97463511558397 | | 2011 | 0.99136111547114 | | 2010 | 1.0090337555584 | | 2009 | 1.026941207517 | | 2008 | 1.0008467897602 | | 2007 | 0.98058931316066 | | 2006 | 0.97979595566786 | | 2005 | 0.97751001174206 | | 2004 | 0.99667425596958 | | 2003 | 1.0479132021626 | | 2002 | 1.0879296360724 | | 2001 | 1.1153130482086 | | 2000 | 1.1490417253673 | | 1999 | 1.1909271098496 | | 1998 | 1.2578358486226 | | 1997 | 1.3173172769408 | | 1996 | 1.3687530487435 | | 1995 | 1.440054339728 | | 1994 | 1.505133511546 | | 1993 | 1.5557094704615 | | 1992 | 1.6117233746071 | | 1991 | 1.6285698920729 | | 1990 | 1.6187506080078 | | 1989 | 1.6142703626087 | | 1988 | 1.6043698836022 | | 1987 | 1.5719969498758 | | 1986 | 1.5145152607946 | | 1985 | 1.4598353224326 | | 1984 | 1.4197144139182 | | 1983 | 1.4220350771313 | | 1982 | 1.4484778554633 | | 1981 | 1.4522417157261 | | 1980 | 1.453400876431 | | 1979 | 1.4845866959112 | | 1978 | 1.518845637845 | | 1977 | 1.5154737417475 | | 1976 | 1.5420461874069 | | 1975 | 1.5800426796221 | | 1974 | 1.5871012426418 | | 1973 | 1.5848587732904 | | 1972 | 1.603470555178 | | 1971 | 1.6551568650429 | | 1970 | 1.6859654318072 | | 1969 | 1.7213576555513 | | 1968 | 1.7561937125375 | | 1967 | 1.7808750519799 | | 1966 | 1.8364432004854 | | 1965 | 1.9067937042895 | | 1964 | 1.9340400005666 | | 1963 | 1.9821527646532 | | 1962 | 2.0546978108884 | | 1961 | 2.0871167263144 |
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