| Year | Value | | 2020 | 1.1048350343189 | | 2019 | 1.0747574406801 | | 2018 | 1.0892218264956 | | 2017 | 1.08054956751 | | 2016 | 0.94680574792244 | | 2015 | 0.93914098116083 | | 2014 | 0.93196893081861 | | 2013 | 0.91400278379134 | | 2012 | 0.89781113644934 | | 2011 | 0.88350372333712 | | 2010 | 0.90427126070915 | | 2009 | 0.92644551970947 | | 2008 | 1.0863661053775 | | 2007 | 1.1179617321699 | | 2006 | 1.154181310342 | | 2005 | 1.1936094151911 | | 2004 | 0.88602734871083 | | 2003 | 1.0472802132861 | | 2002 | 1.0616645079488 | | 2001 | 1.0770821536719 | | 2000 | 1.0940713834689 | | 1999 | 1.1130474603437 | | 1998 | 1.1338125581079 | | 1997 | 1.1883423614343 | | 1996 | 1.2082158679017 | | 1995 | 1.3242919282709 | | 1994 | 1.3699146200713 | | 1993 | 1.723698090832 | | 1992 | 1.7369373625648 | | 1991 | 1.7432353751268 |
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