Year Number 2005 0.891533195972443 2006 0.784292936325073 2007 0.674840748310089 2008 0.495077729225159 2009 0.362061500549316 2010 0.342274248600006 2011 0.253164112567902 2012 0.278990119695663 2013 0.326610743999481 2014 0.394003808498383 2015 0.308005571365356 2016 0.319670587778091 2017 0.321420848369598 2018 0.339362770318985 2019 0.347258865833282 2020 0.384934306144714 2021 0.365972727537155 2022 0.342233091592789