| Year | Value | | 2021 | 61.371114002503 | | 2020 | 61.472259192308 | | 2019 | 61.573071651338 | | 2018 | 61.674380723466 | | 2017 | 61.76997829984 | | 2016 | 61.859298977261 | | 2015 | 61.958237764737 | | 2014 | 61.956305858987 | | 2013 | 61.946375372393 | | 2012 | 61.91892066297 | | 2011 | 61.908071081108 | | 2010 | 61.897529062553 | | 2009 | 61.829264660624 | | 2008 | 61.758545035788 | | 2007 | 61.708043694141 | | 2006 | 61.638530287984 | | 2005 | 61.569016881827 | | 2004 | 61.49950347567 | | 2003 | 61.429990069513 | | 2002 | 61.360476663357 | | 2001 | 61.2909632572 | | 2000 | 61.221449851043 | | 1999 | 60.998013902681 | | 1998 | 60.77457795432 | | 1997 | 60.551142005958 | | 1996 | 60.327706057597 | | 1995 | 60.104270109235 | | 1994 | 59.880834160874 | | 1993 | 59.657398212512 | | 1992 | 59.433962264151 |
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