Year Number 1996 0.882181823253632 1998 1.11591935157776 2000 1.18071973323822 2002 1.07719624042511 2003 1.03226470947266 2004 0.501932442188263 2005 0.811711966991425 2006 0.758358776569366 2007 0.0831864848732948 2008 -0.164438739418983 2009 -0.229707628488541 2010 -0.166243851184845 2011 -0.242630183696747 2012 -0.36517146229744 2013 0.125037372112274 2014 0.679096162319183 2015 0.411403715610504 2016 0.408033192157745 2017 0.224531188607216 2018 0.0829711183905602 2019 0.0276085305958986 2020 0.362981379032135 2021 0.534778356552124 2022 0.667752325534821