| Year | Value | | 2022 | 0.52904660631714 | | 2021 | 0.20002160762067 | | 2020 | 0.98019811161731 | | 2019 | 0.55716366596449 | | 2018 | 0.61812853613192 | | 2017 | 0.69184971060872 | | 2016 | 0.76819134889749 | | 2015 | 0.73984716254256 | | 2014 | 0.76336551220308 | | 2013 | 0.73172841127422 | | 2012 | 0.77150474505901 | | 2011 | 0.75429191964538 | | 2010 | 0.86090695795052 | | 2009 | 0.90683027646689 | | 2008 | 0.96390796813455 | | 2007 | 0.9575110399099 | | 2006 | 0.97341807631672 | | 2005 | 0.92817827330047 | | 2004 | 0.93047382466476 | | 2003 | 0.86729909109904 | | 2002 | 0.94788818869162 | | 2001 | 1.004246352339 | | 2000 | 1.1009288191018 | | 1999 | 1.1214603519149 | | 1998 | 1.1389305940919 | | 1997 | 1.1900776657941 | | 1996 | 1.1582632051786 | | 1995 | 1.1821491108285 | | 1994 | 1.2205627250581 | | 1993 | 1.3051044556816 | | 1992 | 1.3755703717254 | | 1991 | 1.3353753984195 | | 1990 | 1.1740972946281 | | 1989 | 1.0339183222038 | | 1988 | 0.95078358494227 | | 1987 | 0.93987149230092 | | 1986 | 0.9353414482635 | | 1985 | 0.8927881013005 | | 1984 | 0.87730279131388 | | 1983 | 0.9258773613588 | | 1982 | 0.98113412442231 | | 1981 | 1.0109909223617 | | 1980 | 0.99674684978173 | | 1979 | 1.0983459841127 | | 1978 | 1.0587569061384 | | 1977 | 1.0268508134753 | | 1976 | 0.99040020922421 | | 1975 | 1.0366483639683 | | 1974 | 0.96427718704761 | | 1973 | 0.98459196450642 | | 1972 | 1.0845770997848 | | 1971 | 1.4338284068878 | | 1970 | 1.1941419116103 | | 1969 | 1.0184963634804 | | 1968 | 1.0617038361864 | | 1967 | 1.1617334151824 | | 1966 | 1.2278122198129 | | 1965 | 1.3103105183163 | | 1964 | 1.4449683246924 | | 1963 | 1.4888503137936 | | 1962 | 1.5796938232491 | | 1961 | 1.7030827718172 |
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