Year Number 1996 0.135673850774765 1998 0.335129141807556 2000 0.0691719427704811 2002 -0.0784095153212547 2003 -0.058016262948513 2004 -0.430164128541946 2005 -0.0601043850183487 2006 -0.301130533218384 2007 -0.382520467042923 2008 -0.560679852962494 2009 -0.477560758590698 2010 -0.435533314943314 2011 -0.456474870443344 2012 -0.532351732254028 2013 -0.614103138446808 2014 -0.69313257932663 2015 -0.732971966266632 2016 -0.717620611190796 2017 -0.71371054649353 2018 -0.889868915081024 2019 -0.958428800106049 2020 -0.881805598735809 2021 -0.821126997470856 2022 -0.702257215976715