| Year | Value | | 2022 | 0.55746126060478 | | 2021 | 0.55088364880624 | | 2020 | 0.45876201515041 | | 2019 | 0.47331390555208 | | 2018 | 0.6328575401476 | | 2017 | 0.92061312442598 | | 2016 | 0.67359672701681 | | 2015 | 0.79848470490942 | | 2014 | 0.70092494879797 | | 2013 | 0.68723968349625 | | 2012 | 0.70205615778774 | | 2008 | 0.66395897962647 | | 2006 | 0.66572332394775 | | 2005 | 0.68097068499348 | | 2004 | 0.67614985043211 | | 2003 | 0.64722322680876 | | 2002 | 0.62281945820978 | | 2001 | 0.35797112730621 | | 2000 | 0.41285230240838 | | 1999 | 0.48538923049763 | | 1990 | 1.2251571212606 | | 1989 | 1.3078960611849 | | 1988 | 1.5640912047021 | | 1987 | 1.5695985002417 | | 1986 | 1.3550965400695 | | 1985 | 1.3049319324109 | | 1984 | 1.458698940238 | | 1983 | 1.1889706765481 | | 1982 | 1.0492986496015 | | 1981 | 1.5513713192304 | | 1980 | 2.0316514191024 | | 1979 | 1.9304600344134 | | 1978 | 1.1943069306931 | | 1977 | 1.6787878787879 | | 1976 | 1.2816479400749 | | 1975 | 1.4929078014184 | | 1974 | 1.4423791821561 | | 1973 | 1.6775280898876 | | 1972 | 1.4877943088257 | | 1971 | 1.6010420341375 | | 1970 | 1.6252815194159 | | 1969 | 1.8947368421053 | | 1968 | 2.0721247563353 | | 1967 | 1.976252105674 | | 1966 | 1.9002325967769 | | 1965 | 2.1065088757396 | | 1964 | 2.1816990098083 | | 1963 | 1.7368421052632 | | 1962 | 1.7516339869281 | | 1961 | 1.3952879581152 | | 1960 | 0.87158469945355 |
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