Year % net 1999 40.01806 2000 41.15796 2001 41.6674 2002 42.80613 2003 44.34872 2004 45.50777 2005 46.39556 2006 47.49076 2007 49.41777 2008 50.65561 2009 50.61451 2010 52.42785 2011 54.13049 2012 55.38944 2013 56.91442 2014 57.27701 2015 57.60987 2016 58.26122 2017 59.56994 2018 59.91367