Year % net 2000 79.32603 2001 79.26055 2002 80.22968 2003 81.72034 2004 83.18216 2005 83.22422 2006 83.05661 2007 81.85387 2008 85.21789 2009 80.48338 2010 79.31622 2011 78.39118 2012 78.3322 2013 77.7174 2014 77.1835 2015 76.6095 2016 76.56169 2017 77.78425 2018 77.59551