| Year | Value | | 2022 | 71.19415540268 | | 2021 | 71.276016531789 | | 2020 | 73.85472688395 | | 2019 | 71.266527324393 | | 2018 | 71.972128326845 | | 2017 | 71.644829373011 | | 2016 | 71.2503948948 | | 2015 | 70.913011847849 | | 2014 | 70.49678270253 | | 2013 | 70.035623131833 | | 2012 | 69.779443140602 | | 2011 | 69.429886144051 | | 2010 | 69.083544444754 | | 2009 | 68.831693654023 | | 2008 | 68.492810763865 | | 2007 | 68.209017037259 | | 2006 | 68.220573083872 | | 2005 | 67.552059523622 | | 2004 | 66.989953247787 | | 2003 | 66.298076095007 | | 2002 | 65.701674224529 | | 2001 | 65.418817881995 | | 2000 | 65.254237288136 | | 1999 | 67.559348109984 | | 1998 | 66.380726758626 | | 1997 | 66.76753464526 | | 1996 | 63.176664914783 | | 1995 | 65.674299280135 | | 1994 | 62.203058250489 | | 1993 | 66.091989409519 | | 1992 | 66.366442555711 | | 1991 | 66.504706292487 |
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