| Year | Value | | 2022 | 70.191391865846 | | 2021 | 69.960075051674 | | 2020 | 69.755296507444 | | 2019 | 70.675754841917 | | 2018 | 69.947415397087 | | 2017 | 69.609500815526 | | 2016 | 69.215426762907 | | 2015 | 68.988472186186 | | 2014 | 68.773609851919 | | 2013 | 68.470127350016 | | 2012 | 67.779010449958 | | 2011 | 66.995063900558 | | 2010 | 66.037276199671 | | 2009 | 65.039970340543 | | 2008 | 63.84930676394 | | 2007 | 62.471076026145 | | 2006 | 62.729518314218 | | 2005 | 62.805145792191 | | 2004 | 62.704126761423 | | 2003 | 62.661676951112 | | 2002 | 62.763804776639 | | 2001 | 62.763820584715 | | 2000 | 62.383350814876 | | 1999 | 62.844250979287 | | 1998 | 62.893857850292 | | 1997 | 62.284988927395 | | 1996 | 62.169822710689 | | 1995 | 61.897448015123 | | 1994 | 61.486181049281 | | 1993 | 61.083481063333 | | 1992 | 60.720799388135 | | 1991 | 60.235756426531 |
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