| Year | Value | | 2021 | 36.998146749052 | | 2020 | 57.115188706289 | | 2019 | 65.735169458079 | | 2018 | 63.633515738802 | | 2017 | 69.233105398826 | | 2016 | 46.56072980673 | | 2015 | 76.062408596069 | | 2014 | 61.700311955178 | | 2013 | 27.704473261647 | | 2012 | 26.652015213382 | | 2011 | 7.8693018229398 | | 2010 | 14.648460327901 | | 2009 | 3.4690277042494 | | 2008 | 8.3859979342273 | | 2007 | 11.063390576424 | | 2006 | 4.2667135765687 | | 1992 | 95.996302509675 | | 1991 | 100.67082318109 | | 1990 | 57.258187443746 | | 1989 | 48.778577315541 | | 1988 | 51.199994823277 | | 1987 | 49.919607843137 | | 1986 | 29.891487516015 | | 1985 | 30.654347832438 | | 1984 | 50.452078449588 | | 1983 | 74.476190507292 | | 1982 | 55.502505612343 | | 1981 | 27.386858524888 | | 1980 | 34.543229538793 | | 1979 | 50.270144852948 |
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