Year Number 1996 -0.529502689838409 1998 -0.638316988945007 2000 -0.370226055383682 2002 0.222937241196632 2003 0.0786488428711891 2004 -0.134529516100883 2005 -0.013819258660078 2006 0.0919348746538162 2007 0.108356989920139 2008 0.152134746313095 2009 0.0834904238581657 2010 0.111124783754349 2011 0.131239607930183 2012 0.11426293104887 2013 0.0847850143909454 2014 0.192534193396568 2015 0.227381259202957 2016 0.268992602825165 2017 0.274451971054077 2018 0.215548977255821 2019 0.265319764614105 2020 0.247331380844116 2021 0.175867527723312 2022 0.0513254441320896