| Year | Value | | 2020 | 1.0665832361557 | | 2019 | 1.0530306221305 | | 2018 | 1.1280203574497 | | 2017 | 1.0302940802736 | | 2016 | 1.1731136160537 | | 2015 | 1.1792207431865 | | 2014 | 1.1858755249243 | | 2013 | 0.3859256426539 | | 2012 | 0.38898534939725 | | 2011 | 0.39115978877371 | | 2010 | 0.92616670288216 | | 2009 | 0.92863444305149 | | 2008 | 1.0751262377391 | | 2007 | 1.0795017020144 | | 2006 | 1.0843713176557 | | 2005 | 1.0885894058479 | | 2004 | 0.72789474641967 | | 2003 | 1.1311309119834 | | 2002 | 1.1315974871235 | | 2001 | 1.1267523725407 | | 2000 | 1.1212952044736 | | 1999 | 1.1156015071417 | | 1998 | 1.1100249576579 | | 1997 | 1.1046770601336 | | 1996 | 1.0998641135627 | | 1995 | 1.0959601494748 | | 1994 | 0.70526586760044 | | 1993 | 0.70416584513985 | | 1992 | 0.71087604809787 | | 1991 | 1.4347768383975 |
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