| Year | Value | | 2022 | 86.907461797677 | | 2021 | 87.378352332961 | | 2020 | 87.595537443348 | | 2019 | 87.907042945212 | | 2018 | 88.35401401976 | | 2017 | 88.266344321831 | | 2016 | 88.186210174663 | | 2015 | 88.410020808691 | | 2014 | 88.389290884015 | | 2013 | 88.727050794915 | | 2012 | 88.516999325456 | | 2011 | 88.335159358297 | | 2010 | 88.474473135222 | | 2009 | 88.9976812667 | | 2008 | 89.380446133439 | | 2007 | 88.999969773852 | | 2006 | 88.626190591325 | | 2005 | 89.11640884129 | | 2004 | 88.962630777865 | | 2003 | 88.506433069854 | | 2002 | 89.229882264166 | | 2001 | 89.100626360948 | | 2000 | 88.588564367881 | | 1999 | 87.818436220675 | | 1998 | 87.515074092285 | | 1997 | 87.047469578294 | | 1996 | 86.787117796829 | | 1995 | 86.350340298074 | | 1994 | 85.892274558274 | | 1993 | 85.846661250632 | | 1992 | 84.920978128225 | | 1991 | 84.738798083931 |
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