Year % 2007 7.48 2008 9.24 2009 9.16 2010 9.27 2011 9.18 2012 9.04 2013 7.43 2014 7.09 2015 6.77 2016 6.45 2017 6.31 2018 6.23 2019 6.2 2020 5.86 2021 6.2