Year % net 1999 79.1101 2000 80.8336 2001 82.48241 2002 82.43028 2003 82.70971 2004 81.06585 2005 79.44146 2006 80.43643 2007 81.28529 2008 81.54612 2009 81.41374 2010 83.4318 2011 85.06366 2012 85.79707 2013 87.78127 2014 88.49721 2015 88.72278 2016 87.98714 2017 88.23702 2018 87.63771