| Year | Value | | 2022 | 62.883764105499 | | 2021 | 68.175370808827 | | 2020 | 68.142500293365 | | 2019 | 68.102827025687 | | 2018 | 66.516281742075 | | 2017 | 66.178460749136 | | 2016 | 65.90960472013 | | 2015 | 65.043695170498 | | 2014 | 64.032859989066 | | 2013 | 63.010982100425 | | 2012 | 63.356354535633 | | 2011 | 63.793749719992 | | 2010 | 64.398967572793 | | 2009 | 64.727256552842 | | 2008 | 64.987800938095 | | 2007 | 64.662600777303 | | 2006 | 63.961600476685 | | 2005 | 63.998220616882 | | 2004 | 63.764382716601 | | 2003 | 61.395917508767 | | 2002 | 61.066017759376 | | 2001 | 60.390873157187 | | 2000 | 58.047281418383 | | 1999 | 57.852755837135 | | 1998 | 56.437086744425 | | 1997 | 54.794232483025 | | 1996 | 54.281637990174 | | 1995 | 53.890243190716 | | 1994 | 53.265512999588 | | 1993 | 53.28260219681 | | 1992 | 52.604683976247 | | 1991 | 53.170742771098 |
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