| Year | Value | | 2021 | 71.501310959622 | | 2020 | 71.449396958574 | | 2019 | 71.397482957525 | | 2018 | 71.345568956476 | | 2017 | 71.286178691275 | | 2016 | 71.234270134228 | | 2015 | 71.232783272556 | | 2014 | 71.18089041635 | | 2013 | 71.128997560144 | | 2012 | 71.077104703938 | | 2011 | 71.025211847732 | | 2010 | 70.973318991526 | | 2009 | 70.71283154498 | | 2008 | 70.452344098434 | | 2007 | 70.191856651888 | | 2006 | 69.931369205341 | | 2005 | 69.670881758795 | | 2004 | 69.410394312249 | | 2003 | 66.2258040201 | | 2002 | 65.976331658291 | | 2001 | 65.726859296482 | | 2000 | 65.477386934673 | | 1999 | 65.227939698493 | | 1998 | 64.978492462312 | | 1997 | 64.729045226131 | | 1996 | 64.47959798995 | | 1995 | 64.230150753769 | | 1994 | 63.980703517588 | | 1993 | 54.288123622199 | | 1992 | 54.075637266443 | | 1991 | 53.863150910686 | | 1990 | 53.65066455493 |
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