Year Number 1996 -0.0978488251566887 1998 -0.394105225801468 2000 -0.20991687476635 2002 -0.327627182006836 2003 -0.56535792350769 2004 -0.39068067073822 2005 -0.501756608486176 2006 -0.540030121803284 2007 -0.500553727149963 2008 -0.49308842420578 2009 -0.451781332492828 2010 -0.65706068277359 2011 -0.602054834365845 2012 -0.538782060146332 2013 -0.543789923191071 2014 -0.522584021091461 2015 -0.552559673786163 2016 -0.502221345901489 2017 -0.232558473944664 2018 -0.298641502857208 2019 -0.259810864925385 2020 -0.473098784685135 2021 -0.51672887802124 2022 -0.441073626279831