| Year | Value | | 2021 | 70.112731152205 | | 2020 | 70.412873399715 | | 2019 | 70.713015647226 | | 2018 | 71.013157894737 | | 2017 | 71.313300142247 | | 2016 | 71.613442389758 | | 2015 | 71.913584637269 | | 2014 | 72.21386913229 | | 2013 | 72.514153627312 | | 2012 | 72.814438122333 | | 2011 | 73.114722617354 | | 2010 | 73.415007112376 | | 2009 | 73.715327169275 | | 2008 | 74.015647226173 | | 2007 | 74.315967283073 | | 2006 | 74.616287339972 | | 2005 | 74.916607396871 | | 2004 | 75.21692745377 | | 2003 | 75.517247510669 | | 2002 | 75.817567567568 | | 2001 | 76.117887624467 | | 2000 | 76.418207681366 | | 1999 | 76.718527738265 | | 1998 | 77.018847795164 | | 1997 | 77.319167852063 | | 1996 | 77.619487908962 | | 1995 | 77.919807965861 | | 1994 | 78.22012802276 | | 1993 | 78.520448079659 | | 1992 | 78.820768136558 | | 1991 | 79.121088193457 | | 1990 | 79.421408250356 |
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