| Year | Value | | 2023 | 1.8276762402089 | | 2022 | 1.8276762402089 | | 2021 | 1.8276762402089 | | 2020 | 1.8276762402089 | | 2019 | 1.8276762402089 | | 2018 | 1.8276762402089 | | 2017 | 1.6536118363795 | | 2016 | 1.5926892950392 | | 2015 | 1.6100957354221 | | 2014 | 1.6100957354221 | | 2013 | 1.4728682170543 | | 2012 | 1.4177433247201 | | 2011 | 1.3850129198966 | | 2010 | 1.3204134366925 | | 2009 | 1.2833763996555 | | 2008 | 1.2144702842377 | | 2007 | 1.1541774332472 | | 2006 | 1.0938845822567 | | 2005 | 1.0335917312662 | | 2004 | 1.0508182601206 | | 2003 | 1.1369509043928 | | 2002 | 1.0938845822567 | | 2001 | 1.14556416882 | | 2000 | 1.1197243755383 | | 1999 | 1.1197243755383 | | 1998 | 1.1197243755383 | | 1997 | 1.1197243755383 | | 1996 | 1.1197243755383 | | 1995 | 1.1197243755383 | | 1994 | 1.1197243755383 | | 1993 | 1.1197243755383 | | 1992 | 1.0335917312662 | | 1991 | 0.77519379844961 | | 1990 | 0.86132644272179 | | 1989 | 0.77519379844961 | | 1988 | 0.77519379844961 | | 1987 | 0.77519379844961 | | 1986 | 0.68906115417743 | | 1985 | 0.68906115417743 | | 1984 | 0.68906115417743 | | 1983 | 0.60292850990525 | | 1982 | 0.51679586563308 | | 1981 | 0.4306632213609 | | 1980 | 0.34453057708872 | | 1979 | 0.17226528854436 | | 1978 | 0.086132644272179 | | 1977 | 0.17226528854436 | | 1976 | 0.17226528854436 | | 1975 | 0.17226528854436 |
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