Year Number 1996 0.36849319934845 1998 0.352811932563782 2000 0.345234483480453 2002 0.382046699523926 2003 0.059730738401413 2004 -0.16634014248848 2005 -0.224495947360992 2006 0.240350216627121 2007 -0.279368013143539 2008 -0.643881678581238 2009 -0.882854044437408 2010 -1.07616984844208 2011 -1.17367887496948 2012 -1.13399171829224 2013 -1.01476144790649 2014 -0.589508354663849 2015 -0.635684847831726 2016 -0.748691558837891 2017 -0.629497826099396 2018 -0.632418096065521 2019 -0.562930703163147 2020 -0.700950503349304 2021 -0.555529892444611 2022 -0.507473766803741