| Year | Value | | 2022 | 0.061238864095749 | | 2021 | 0.12236533693628 | | 2020 | 0.073401232766147 | | 2019 | 0.11326589611883 | | 2018 | 0.14099619194068 | | 2017 | 0.11355441857333 | | 2016 | 0.13828073187548 | | 2015 | 0.20932101467915 | | 2014 | 0.12642031808751 | | 2013 | 0.7774427041178 | | 2012 | 1.4375218183762 | | 2011 | 1.3944923653724 | | 2010 | 1.4271919571043 | | 2009 | 1.3754566127967 | | 2008 | 1.3312777335126 | | 2007 | 1.3728963770137 | | 2006 | 1.4708650994887 | | 2005 | 1.5171965959883 | | 2004 | 1.4557319000289 | | 2003 | 1.4557230355183 | | 2002 | 0.61496606516753 | | 2001 | 0.072121455652224 | | 2000 | 0.16595717785441 | | 1999 | 0.21326208585188 | | 1998 | 0.2608697131587 | | 1997 | 0.2651895115115 | | 1996 | 0.28778046562692 | | 1995 | 0.47537296526487 | | 1994 | 0.6029430030811 | | 1993 | 0.63999626546575 | | 1992 | 0.1594571379719 | | 1991 | -1.2116896244638 | | 1990 | -1.3489887323227 | | 1989 | -1.1205403842161 | | 1988 | 0.96674054021366 | | 1987 | 0.82426758554987 | | 1986 | 0.58761973912369 | | 1985 | 0.39678448214817 | | 1984 | 0.23246545173719 | | 1983 | 0.027720988430752 | | 1982 | 0.15256062041562 | | 1981 | 0.29538012545535 | | 1980 | 0.4045200103984 | | 1979 | 0.46582575521844 | | 1978 | 0.52092617184262 | | 1977 | 0.61948197188127 | | 1976 | 0.67337922567668 | | 1975 | 0.69594196802977 | | 1974 | 0.7987464986344 | | 1973 | 0.85640362345114 | | 1972 | 0.93396766567266 | | 1971 | 1.4287551894565 | | 1970 | 1.9793633519873 | | 1969 | 2.1325076054601 | | 1968 | 2.2228840331461 | | 1967 | 2.30201587652 | | 1966 | 2.3437119644539 | | 1965 | 2.3828285266933 | | 1964 | 2.3883414230547 | | 1963 | 2.4288018190733 | | 1962 | 1.5490843328658 | | 1961 | 0.38875852204555 |
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