| Year | Value | | 2022 | 0.41121129876252 | | 2021 | 0.63092883537222 | | 2020 | 0.73449261223255 | | 2019 | 0.6996961343792 | | 2018 | 0.73230034753854 | | 2017 | 0.85613791637354 | | 2016 | 0.81314007792887 | | 2015 | 0.85012858318676 | | 2014 | 0.87810091936404 | | 2013 | 0.83773643015944 | | 2012 | 0.78482472101979 | | 2011 | 0.76428709403675 | | 2010 | 0.81487810549794 | | 2009 | 0.88650857668639 | | 2008 | 0.76275647539046 | | 2007 | 0.79254817503136 | | 2006 | 0.78823387746147 | | 2005 | 0.84715478388596 | | 2004 | 0.88329535883353 | | 2003 | 1.0608950570484 | | 2002 | 1.0918804785975 | | 2001 | 1.1842335418706 | | 2000 | 1.1488226766689 | | 1999 | 1.2203595475499 | | 1998 | 1.1363180218633 | | 1997 | 1.1401391113129 | | 1996 | 1.2412272643763 | | 1995 | 1.4730731072115 | | 1994 | 1.4570385332505 | | 1993 | 1.4228029005729 | | 1992 | 1.4212222334878 | | 1991 | 1.5069265552964 | | 1990 | 1.4509092122579 | | 1989 | 1.8803655923922 | | 1988 | 2.1249392231366 | | 1987 | 2.2843868799904 | | 1986 | 2.3136787492112 | | 1985 | 2.2997172478794 | | 1984 | 2.1620391442877 | | 1983 | 2.7388127853881 | | 1982 | 2.7045579352004 | | 1981 | 3.4653465346535 | | 1980 | 3.0989583333333 | | 1979 | 4.6733562557013 | | 1978 | 4.7191440580818 | | 1977 | 4.0086000955566 | | 1976 | 3.7812911725955 | | 1975 | 2.041958041958 | | 1974 | 1.6591836734694 | | 1973 | 1.8485714285714 | | 1972 | 1.8238095238095 | | 1971 | 1.8076923076923 | | 1970 | 1.8777777777778 | | 1969 | 1.9375 | | 1968 | 1.6857142857143 | | 1967 | 1.4 | | 1966 | 1.168 | | 1965 | 1.07 | | 1964 | 1.15 | | 1963 | 1.68 | | 1962 | 2.66 | | 1961 | 2.14 | | 1960 | 1.55 |
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