Year % net 1999 37.94873 2000 39.21835 2001 39.45048 2002 40.80542 2003 42.38781 2004 43.5326 2005 45.2492 2006 46.59837 2007 48.49171 2008 50.24801 2009 49.83545 2010 52.14638 2011 54.02543 2012 55.94732 2013 57.56894 2014 58.0758 2015 58.30514 2016 58.68417 2017 60.20007 2018 60.5279