Year Number 1996 -0.819772601127625 1998 -0.77269583940506 2000 -1.31242227554321 2002 -1.45189714431763 2003 -1.45855021476746 2004 -1.59736406803131 2005 -1.76681733131409 2006 -1.75380945205688 2007 -1.70445394515991 2008 -1.59331786632538 2009 -1.54764413833618 2010 -1.55507206916809 2011 -1.66020834445953 2012 -1.56718134880066 2013 -1.54442870616913 2014 -1.44286942481995 2015 -1.46507394313812 2016 -1.3393886089325 2017 -1.35598385334015 2018 -1.363152384758 2019 -1.40739941596985 2020 -1.45349812507629 2021 -1.58077239990234 2022 -1.6263952255249