| Year | Value | | 2020 | 0.88266169373039 | | 2019 | 0.86926312564839 | | 2018 | 0.88871315869531 | | 2017 | 0.8633706373402 | | 2016 | 0.83138255161595 | | 2015 | 0.87269879272666 | | 2014 | 0.88964488312618 | | 2013 | 0.88319878288614 | | 2012 | 0.88425931555897 | | 2011 | 0.94827027304967 | | 2010 | 0.97147675536688 | | 2009 | 0.96472480893142 | | 2008 | 1.0093959231275 | | 2007 | 1.0361959175475 | | 2006 | 1.0847647708455 | | 2005 | 1.0157572388955 | | 2004 | 0.98091787755529 | | 2003 | 1.4732542598662 | | 2002 | 1.4801624987979 | | 2001 | 1.5089784216086 | | 2000 | 1.6147568476071 | | 1999 | 1.6491829711963 | | 1998 | 1.6880054672086 | | 1997 | 1.7313704539159 | | 1996 | 1.7855384648348 | | 1995 | 1.483021759021 | | 1994 | 0.86673419970639 | | 1993 | 0.89379732587013 | | 1992 | 0.92101226155136 | | 1991 | 0.94477941467372 |
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