| Year | Value | | 2021 | 1.7375017 | | 2020 | 2.28629 | | 2017 | 7.745645613 | | 2016 | 6.872800012 | | 2015 | 5.8787059818438 | | 2009 | 0.013 | | 2008 | 0.013 | | 2007 | 0.013 | | 2006 | 0.013 | | 2005 | 0.013 | | 2004 | 0.011 | | 2003 | 0.009 | | 2002 | 0.009 | | 2001 | 0.008 | | 2000 | 13.17 | | 1999 | 11.8999996185 | | 1998 | 10.3000001907 | | 1997 | 6.5999999046 | | 1996 | 6.8000001907 | | 1995 | 2.9000000954 | | 1994 | 0.200000003 | | 1986 | 1.3999999762 | | 1985 | 1.2999999523 | | 1984 | 0.400000006 | | 1983 | 0.400000006 | | 1982 | 0.400000006 | | 1981 | 0.400000006 | | 1980 | 0.3000000119 | | 1979 | 0.3000000119 | | 1978 | 0.200000003 | | 1977 | 0.200000003 | | 1976 | 0.200000003 | | 1975 | 0.1000000015 |
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