| Year | Value | | 2020 | 0.69527327000427 | | 2019 | 0.76778190378771 | | 2018 | 0.76486510562474 | | 2017 | 0.78283068228919 | | 2016 | 0.81897014180449 | | 2015 | 0.84511131526059 | | 2014 | 0.84993301490821 | | 2013 | 0.88499248845555 | | 2012 | 0.91219361050963 | | 2011 | 0.9286828115892 | | 2010 | 0.956894673937 | | 2009 | 0.94139603797622 | | 2008 | 0.92445360563399 | | 2007 | 0.93514323047362 | | 2005 | 0.97733482023203 | | 2004 | 1.0004908453516 | | 2003 | 1.0675749251499 | | 2002 | 1.1010464498154 | | 2001 | 1.0785167515184 | | 2000 | 1.242456629548 | | 1999 | 1.2512683079007 | | 1998 | 1.2353513134154 | | 1997 | 1.2734971144391 | | 1996 | 1.2943716572055 | | 1995 | 1.304430173177 | | 1994 | 0.79403248733994 | | 1993 | 0.86899267285553 | | 1992 | 0.87510902767354 | | 1991 | 0.93800449600948 |
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