Year Number 2004 1.26952648162842 2005 1.11161744594574 2006 0.608042120933533 2007 0.62667590379715 2008 0.642759263515472 2009 0.653302133083344 2010 0.642825543880463 2011 0.631379723548889 2012 0.59927225112915 2013 0.601454555988312 2014 0.529373943805695 2015 0.524791419506073 2016 0.860476732254028 2017 0.831546187400818 2018 0.813936293125153 2019 1.22192621231079 2020 1.33542132377625 2021 1.35934960842133 2022 1.39833402633667