| Year | Value | | 2021 | 92.071428571429 | | 2020 | 92.028571428571 | | 2019 | 91.985714285714 | | 2018 | 91.942857142857 | | 2017 | 91.9 | | 2016 | 91.857142857143 | | 2015 | 91.814285714286 | | 2014 | 91.774285714286 | | 2013 | 91.734285714286 | | 2012 | 91.694285714286 | | 2011 | 91.654285714286 | | 2010 | 91.614285714286 | | 2009 | 91.575714285714 | | 2008 | 91.537142857143 | | 2007 | 91.498571428571 | | 2006 | 91.46 | | 2005 | 91.421428571429 | | 2004 | 91.382857142857 | | 2003 | 91.344285714286 | | 2002 | 91.305714285714 | | 2001 | 91.267142857143 | | 2000 | 91.228571428571 | | 1999 | 91.188571428571 | | 1998 | 91.148571428571 | | 1997 | 91.108571428571 | | 1996 | 91.068571428571 | | 1995 | 91.028571428571 | | 1994 | 90.988571428571 | | 1993 | 90.948571428571 | | 1992 | 90.908571428571 | | 1991 | 90.868571428571 |
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