Year Number 1996 -1.15093290805817 1998 -0.586954712867737 2000 -1.90759003162384 2002 -1.42116582393646 2003 -0.78889536857605 2004 -1.03338360786438 2005 -1.15397679805756 2006 -1.90892851352692 2007 -2.40334820747375 2008 -2.09733891487122 2009 -2.116455078125 2010 -1.6870790719986 2011 -1.38805401325226 2012 -1.2870124578476 2013 -1.22985172271729 2014 -0.95524275302887 2015 -0.386475414037704 2016 -0.396070927381516 2017 -0.69907408952713 2018 -0.880607545375824 2019 -0.842596650123596 2020 -0.669287204742432 2021 -0.939894258975983 2022 -0.864391386508942