| Year | Value | | 2022 | 78.943071176339 | | 2021 | 78.59987594379 | | 2020 | 78.476430453646 | | 2019 | 79.408931698774 | | 2018 | 78.137987006366 | | 2017 | 78.305143397309 | | 2016 | 78.525896930175 | | 2015 | 79.118357857383 | | 2014 | 81.149477856544 | | 2013 | 84.010115606936 | | 2012 | 83.764869180333 | | 2011 | 83.574540888558 | | 2010 | 83.933251484553 | | 2009 | 84.142646413906 | | 2008 | 84.061632589233 | | 2007 | 83.84648611725 | | 2006 | 83.571740055021 | | 2005 | 83.358086000046 | | 2004 | 83.280628734857 | | 2003 | 83.173449358426 | | 2002 | 83.107402328363 | | 2001 | 82.959407344891 | | 2000 | 82.681544539554 | | 1999 | 82.481846396664 | | 1998 | 82.281446857983 | | 1997 | 81.945732011695 | | 1996 | 81.71481125371 | | 1995 | 81.645132003776 | | 1994 | 81.882032667877 | | 1993 | 82.231294338107 | | 1992 | 82.612979827654 | | 1991 | 82.784560365026 |
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