Year % net 1993 93.80688 1994 93.46468 1995 92.19694 1996 92.45069 1997 92.16192 1998 92.29827 1999 92.49885 2000 91.8084 2001 92.40911 2002 93.14406 2003 94.76158 2004 94.14444 2005 92.77085 2006 92.80817 2007 92.92426 2008 93.06533 2009 92.74845 2010 93.36737 2011 93.53405 2012 93.43554 2013 93.83136 2014 93.6168 2015 93.84996 2016 93.97116 2017 92.30525 2018 92.15259