Year % 2001 7.44365162359176 2002 7.90303500003821 2003 7.8834135092372 2004 7.42285896371141 2005 7.10101814881614 2006 6.79388006091752 2007 6.90688679593399 2008 7.24915898284898 2009 7.85398409913412 2010 7.83995415608633 2011 7.73891260114948 2012 7.93992737990081 2013 7.91156845586094 2014 7.76993907852362 2015 7.36574053509472 2016 8.2490296702381 2017 8.28941482443367 2018 8.19181738377551 2019 7.33892973803531 2020 6.63929108433719 2021 6.65192868012311