Year Number 1996 0.515013754367828 1998 0.507770359516144 2000 0.540943026542664 2002 0.733767986297607 2003 0.819586336612701 2004 0.692467272281647 2005 0.715097188949585 2006 0.746972680091858 2007 0.595666348934174 2008 0.656967222690582 2009 0.449182033538818 2010 0.445573270320892 2011 0.446406275033951 2012 0.398661673069 2013 0.380482465028763 2014 0.230833724141121 2015 0.208593904972076 2016 0.119783155620098 2017 0.138913422822952 2018 -0.0407781675457954 2019 0.00850539095699787 2020 0.0204948224127293 2021 -0.0907086357474327 2022 -0.185125753283501