| Year | Value | | 2021 | 60.030150123085 | | 2020 | 60.283337144702 | | 2019 | 60.536515153553 | | 2018 | 60.789706614294 | | 2017 | 61.042884623145 | | 2016 | 61.295955016882 | | 2015 | 61.549254092737 | | 2014 | 61.802391745921 | | 2013 | 62.055529399104 | | 2012 | 62.308667052287 | | 2011 | 62.561804705471 | | 2010 | 62.814942358654 | | 2009 | 62.863100122412 | | 2008 | 62.91125788617 | | 2007 | 62.959415649928 | | 2006 | 63.007573413686 | | 2005 | 63.055731177444 | | 2004 | 63.103888941202 | | 2003 | 63.15204670496 | | 2002 | 63.200204468718 | | 2001 | 63.248362232476 | | 2000 | 63.296519996233 | | 1999 | 63.344677759991 | | 1998 | 63.392835523749 | | 1997 | 63.440993287507 | | 1996 | 63.489151051265 | | 1995 | 63.537308815023 | | 1994 | 63.585466578781 | | 1993 | 63.633624342539 | | 1992 | 63.681782106297 | | 1991 | 63.729939870055 | | 1990 | 63.778097633813 |
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