| Year | Value | | 2022 | 10.993203920913 | | 2021 | 22.020767624578 | | 2020 | 15.733060472137 | | 2019 | 9.1503164431628 | | 2018 | 7.4945719272851 | | 2017 | 6.5773115420565 | | 2016 | 17.869730079527 | | 2015 | 10.110592890962 | | 2014 | 7.8068755356633 | | 2013 | 6.9776760549035 | | 2012 | 6.5758997075766 | | 2011 | 6.4293968107234 | | 2010 | 8.5017613336527 | | 2009 | 13.39525463259 | | 2008 | 12.445579346319 | | 2007 | 10.657349600015 | | 2006 | 9.0195724722649 | | 2005 | 18.324439701174 | | 2004 | 17.967789108729 | | 2003 | 21.4015783902 | | 2002 | 22.233344643095 | | 2001 | 21.393782179255 | | 2000 | 26.030411788812 | | 1999 | 26.787696679003 | | 1998 | 24.458456351666 | | 1997 | 24.418721568941 | | 1996 | 43.073097998288 | | 1995 | 34.929587416667 | | 1994 | 54.601321841302 | | 1993 | 183.31204146439 | | 1992 | 165.70652700999 | | 1991 | 97.642323174238 | | 1990 | 107.02380952381 | | 1989 | 123.40425531915 | | 1988 | 51.004016064257 | | 1987 | 47.047244094488 | | 1986 | 55.828220858897 |
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