Year Number 1996 -2.43946290016174 1998 -1.75555086135864 2000 -1.95288050174713 2002 -2.18961954116821 2003 -2.15939283370972 2004 -1.36538577079773 2005 -1.35790872573853 2006 -1.32684123516083 2007 -1.24483954906464 2008 -1.28312230110168 2009 -1.05055463314056 2010 -0.468525290489197 2011 -0.427370250225067 2012 -0.484476506710052 2013 -0.475507080554962 2014 -0.615449607372284 2015 -0.817833304405212 2016 -0.441768199205399 2017 -0.32053479552269 2018 -0.203764617443085 2019 -0.339135408401489 2020 -0.314182639122009 2021 -0.286361515522003 2022 -0.291599869728088