Year Number 1996 1.75708055496216 1998 1.9069150686264 2000 1.95634055137634 2002 1.93704175949097 2003 1.75373554229736 2004 2.1585156917572 2005 1.84628260135651 2006 2.07526707649231 2007 2.03580713272095 2008 2.02759099006653 2009 1.94502568244934 2010 1.8709591627121 2011 1.86164331436157 2012 1.88282430171967 2013 1.81698524951935 2014 2.10511255264282 2015 1.96786153316498 2016 1.97234451770782 2017 2.01732301712036 2018 1.99700856208801 2019 1.91630423069 2020 1.97250926494598 2021 1.99303758144379 2022 2.04994893074036