Year Number 1996 1.26643979549408 1998 1.2458621263504 2000 1.22314357757568 2002 1.18108355998993 2003 1.17078423500061 2004 0.859443843364716 2005 1.11161744594574 2006 1.10253143310547 2007 0.99803227186203 2008 1.02270376682281 2009 0.887313961982727 2010 0.855329275131226 2011 0.854432463645935 2012 0.914866805076599 2013 0.847472012042999 2014 0.890397012233734 2015 0.971896648406982 2016 0.939097106456757 2017 0.859337687492371 2018 0.937738716602325 2019 0.722416639328003 2020 0.784048199653625 2021 0.826616287231445 2022 0.848512649536133