| Year | Value | | 2023 | 0.794172 | | 2022 | 2.444208 | | 2021 | 12.020124731 | | 2020 | 19.878902393 | | 2019 | 20.014205954918 | | 2018 | 29.559348798013 | | 2017 | 21.462556513 | | 2016 | 29.010880897 | | 2015 | 33.102038592 | | 2014 | 34.283472 | | 2013 | 84.621216 | | 2012 | 116.66072342268 | | 2011 | 109.42111746999 | | 2010 | 108.019487128 | | 2000 | 7.813 | | 1999 | 7.4000000954 | | 1998 | 15 | | 1997 | 35.4000015259 | | 1996 | 13.5 | | 1995 | 12.8999996185 | | 1994 | 12.3000001907 | | 1993 | 6.6999998093 | | 1992 | 8.3999996185 | | 1991 | 8.3999996185 | | 1990 | 9.3999996185 | | 1989 | 11.5 | | 1988 | 8.8000001907 | | 1987 | 8.1000003815 | | 1986 | 7.5 | | 1985 | 19.8999996185 | | 1984 | 19.7999992371 | | 1983 | 11.3999996185 | | 1982 | 18.2999992371 | | 1981 | 19.3999996185 | | 1980 | 21.3999996185 | | 1979 | 19.1000003815 | | 1978 | 12.8999996185 | | 1977 | 13.8999996185 | | 1976 | 12.8999996185 |
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