Year Number 1996 0.110229268670082 1998 0.083308145403862 2000 0.186396479606628 2002 -0.208229526877403 2003 -0.384524792432785 2004 -0.34566855430603 2005 -0.298737347126007 2006 -0.320163667201996 2007 -0.256037086248398 2008 -0.307299733161926 2009 -0.363817691802979 2010 -0.4295414686203 2011 -0.0629833340644836 2012 0.12050811201334 2013 0.182374373078346 2014 0.0244925320148468 2015 0.0859657227993011 2016 0.295468419790268 2017 0.298302531242371 2018 0.423851728439331 2019 0.388235539197922 2020 0.258638471364975 2021 0.217914655804634 2022 0.379746347665787