Year Number 1996 0.268791258335114 1998 0.262724310159683 2000 0.207037776708603 2002 -0.199828878045082 2003 -0.218190565705299 2004 -0.231533601880074 2005 -0.533665299415588 2006 -0.510794937610626 2007 -0.45739883184433 2008 -0.494799554347992 2009 -0.69857132434845 2010 -0.683138370513916 2011 -0.669470012187958 2012 -0.74639219045639 2013 -0.77031546831131 2014 -0.790833830833435 2015 -0.774814009666443 2016 -0.687102138996124 2017 -0.726939260959625 2018 -0.713534414768219 2019 -0.692302823066711 2020 -0.705098152160645 2021 -0.72774875164032 2022 -0.614071309566498