| Year | Value | | 2022 | 0.82127144659515 | | 2021 | 0.97045964700827 | | 2020 | 1.1204673256024 | | 2019 | 1.1031789847194 | | 2018 | 1.0422739735043 | | 2017 | 1.0446523267175 | | 2016 | 1.0334356508909 | | 2015 | 1.0117476321259 | | 2014 | 1.0118034959337 | | 2013 | 1.040240812165 | | 2012 | 1.0745363270916 | | 2011 | 1.104701890028 | | 2010 | 1.1220419963936 | | 2009 | 1.1265337843872 | | 2008 | 1.1285721601812 | | 2007 | 1.1282357534127 | | 2006 | 1.1178617008084 | | 2005 | 1.1001365348952 | | 2004 | 1.3392001020076 | | 2003 | 1.623735203631 | | 2002 | 1.6829481903374 | | 2001 | 1.7376408861 | | 2000 | 1.7989733733445 | | 1999 | 1.868523490047 | | 1998 | 1.9378807160883 | | 1997 | 2.0192027591967 | | 1996 | 2.1277689169214 | | 1995 | 1.8448024919252 | | 1994 | 0.98313595271685 | | 1993 | 0.67799607853772 | | 1992 | 0.84739981077833 | | 1991 | 0.77829668022542 | | 1990 | 1.0707481038225 | | 1989 | 1.5351338302581 | | 1988 | 1.3196588034757 | | 1987 | 1.1390842577641 | | 1986 | 1.3343913482526 | | 1985 | 1.1831967056247 | | 1984 | 0.84197099617148 | | 1983 | 0.56059573506345 | | 1982 | 0.37947484749018 | | 1981 | 0.19894250147444 | | 1980 | 0.59802908956943 | | 1979 | -1.1914577221614 | | 1978 | -1.0225504139221 | | 1977 | 0.88279774035781 | | 1976 | 0.74382708238735 | | 1975 | 0.605603282779 | | 1974 | 0.45824193482519 | | 1973 | 0.3018166702982 | | 1972 | 1.3939723286504 | | 1971 | 3.1372724160719 | | 1970 | 3.2911084410443 | | 1969 | 3.3609124423317 | | 1968 | 3.3898835493268 | | 1967 | 3.3973807316169 | | 1966 | 3.3906535015753 | | 1965 | 3.4155154848015 | | 1964 | 3.59475731727 | | 1963 | 3.7582938605894 | | 1962 | 3.6460789993811 | | 1961 | 3.5046094824663 |
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