Year Number 2002 -1.23270869255066 2003 -1.26821637153625 2004 -1.14806532859802 2005 -1.14945936203003 2006 -1.55442380905151 2007 -1.63284885883331 2008 -1.34163308143616 2009 -1.15977454185486 2010 -1.11062812805176 2011 -1.05282890796661 2012 -1.02370250225067 2013 -0.991481781005859 2014 -0.905718266963959 2015 -0.993646323680878 2016 -0.993600726127625 2017 -0.746640622615814 2018 -0.792416214942932 2019 -0.775254309177399 2020 -0.763640761375427 2021 -0.777108013629913 2022 -0.472811251878738