| Year | Value | | 2022 | 71.64606547904 | | 2021 | 71.486250912368 | | 2020 | 71.51271525029 | | 2019 | 71.307782998117 | | 2018 | 71.819610801974 | | 2017 | 71.925757393127 | | 2016 | 72.152870429573 | | 2015 | 72.67563201219 | | 2014 | 73.207446096156 | | 2013 | 72.682690760582 | | 2012 | 72.890944488253 | | 2011 | 71.906561217428 | | 2010 | 71.501382931429 | | 2009 | 70.752184454087 | | 2008 | 70.503425665889 | | 2007 | 70.122887086212 | | 2006 | 70.217757134208 | | 2005 | 71.367418073059 | | 2004 | 70.522552116428 | | 2003 | 70.265228650533 | | 2002 | 70.12023563985 | | 2001 | 71.232617994247 | | 2000 | 73.025456806856 | | 1999 | 72.661225776813 | | 1998 | 72.951756770657 | | 1997 | 72.945426259117 | | 1996 | 72.900688542702 | | 1995 | 72.83966744735 | | 1994 | 72.713189789669 | | 1993 | 72.568790247459 | | 1992 | 72.605875928212 | | 1991 | 72.597641105171 |
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