Year Number 1996 0.659302592277527 1998 0.663797557353973 2000 0.630551934242249 2002 0.610876262187958 2003 0.276081532239914 2004 0.29008686542511 2005 -0.224626928567886 2006 0.184131041169167 2007 0.121460936963558 2008 0.0983418449759483 2009 -0.154777318239212 2010 -0.159897983074188 2011 0.108835898339748 2012 0.181172475218773 2013 0.195707112550735 2014 0.385206580162048 2015 0.37784206867218 2016 0.335442960262299 2017 0.638752341270447 2018 0.699863374233246 2019 0.688096284866333 2020 0.61318838596344 2021 0.443210333585739 2022 0.388570487499237