Year Number 1996 -1.25874590873718 1998 -1.23111176490784 2000 -0.80017364025116 2002 -0.803475081920624 2003 -0.766690611839294 2004 -0.833764553070068 2005 -0.601551175117493 2006 -0.590213000774384 2007 -0.819362878799438 2008 -0.823874354362488 2009 -1.03079056739807 2010 -0.915285527706146 2011 -0.959997057914734 2012 -1.22053194046021 2013 -1.24993252754211 2014 -1.08603596687317 2015 -1.49530971050262 2016 -2.00721478462219 2017 -1.78637540340424 2018 -1.31516599655151 2019 -1.37813580036163 2020 -1.14386320114136 2021 -1.1367609500885 2022 -1.03986501693726