Year % 2006 8.6 2007 8.3 2008 8.5 2009 8.2 2010 8.4 2011 8.5 2012 8.4 2013 8.6 2014 8.6 2015 8.5 2016 8.6 2017 8.5 2018 8.6 2019 8.1 2020 8