| Year | Value | | 2022 | 33.546572998621 | | 2021 | 3.2283469367708 | | 2020 | 3.8118494813668 | | 2019 | 3.5201524158868 | | 2018 | 3.1923532653189 | | 2017 | 2.8844015189716 | | 2016 | 3.1547766025102 | | 2015 | 3.2511807634128 | | 2014 | 2.2450205209479 | | 2013 | 1.5792916793498 | | 2012 | 1.6133199172901 | | 2011 | 1.5336412405932 | | 2010 | 1.9023610223228 | | 2009 | 1.9089819036537 | | 2008 | 2.3027411439941 | | 2007 | 2.4725274026289 | | 2006 | 2.3877456383544 | | 2005 | 2.4057489949888 | | 2004 | 1.9670585997807 | | 2003 | 2.1242090461683 | | 2002 | 1.9846842460429 | | 2001 | 1.8868710784894 | | 2000 | 2.1510492369186 | | 1999 | 1.9007561884642 | | 1998 | 2.1059817130512 | | 1997 | 2.7949791096961 | | 1996 | 2.1907863090507 | | 1995 | 2.0359574317869 | | 1994 | 1.7983402674597 | | 1993 | 0.35235287737778 | | 1992 | 0.31808730838754 |
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