Year % of profit 2005 36.6 2006 36.6 2007 36.6 2008 36.6 2009 36.6 2010 36.8 2011 37.6 2012 36.8 2013 36.7 2014 36.9 2015 34.7 2016 35.1 2017 35.2 2018 35.7 2019 35.8