Year | Value | 2023 | 1.0499651106193 | 2022 | 1.0721673814229 | 2021 | 1.1651358486026 | 2020 | 1.1600576973973 | 2019 | 1.1324421619568 | 2018 | 1.221445659216 | 2017 | 1.3104826630319 | 2016 | 1.3340851574389 | 2015 | 1.3497900203624 | 2014 | 1.3977751944463 | 2013 | 1.4304997159645 | 2012 | 1.4492841933337 | 2011 | 1.4538734073168 | 2010 | 1.4572298835144 | 2009 | 1.5078919487324 | 2008 | 1.6566390573139 | 2007 | 1.7432556185774 | 2006 | 1.7302696916773 | 2005 | 1.7531759490284 | 2004 | 1.7723319460687 | 2003 | 1.7825762292865 | 2002 | 1.7959298791696 | 2001 | 1.7938143339827 | 2000 | 1.830648178896 | 1999 | 1.951251573448 | 1998 | 2.0563612755248 | 1997 | 2.2018666803053 | 1996 | 2.3807325984787 | 1995 | 2.627508394049 | 1994 | 3.7629422779542 | 1993 | 5.2646279586557 | 1992 | 4.836681183643 | 1991 | 3.8370225801223 | 1990 | 3.8888910533693 | 1989 | 3.5768104956227 | 1988 | 3.6221401701927 | 1987 | 4.0202603714537 | 1986 | 3.794021317354 | 1985 | 3.3385758634098 | 1984 | 3.5954143571751 | 1983 | 3.8853885072104 | 1982 | 3.9318625721521 | 1981 | 2.6349900187822 | 1980 | 2.4024304354626 | 1979 | 1.5086441541694 | 1978 | -1.3165998477281 | 1977 | -4.3242843772044 | 1976 | -6.4586858181263 | 1975 | -2.7196385198493 | 1974 | 0.88695959743953 |
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