Year Number 1996 0.13993801176548 1998 0.224192708730698 2000 0.00215644319541752 2002 -0.0776224359869957 2003 -0.0183236226439476 2004 0.125264555215836 2005 -0.170190066099167 2006 0.189769744873047 2007 0.322974681854248 2008 0.314200758934021 2009 0.276933073997498 2010 0.297299355268478 2011 0.291849315166473 2012 0.0459933318197727 2013 0.0749636813998222 2014 0.203010261058807 2015 0.294767826795578 2016 0.4741171002388 2017 0.552543342113495 2018 0.595471441745758 2019 0.589010059833527 2020 0.528976261615753 2021 0.378315657377243 2022 0.604482173919678