Year Percent 1990 0.13037 1991 0.25908 1992 0.64282 1993 0.76534 1994 1.39342 1995 1.89021 1996 6.90916 1997 9.53397 1998 15.42122 1999 23.04432 2000 33.73013 2001 39.18545 2002 36.56 2003 42.7 2004 54.28 2005 58 2006 63.6 2007 69.37 2008 72.87 2009 73.45 2010 75.17 2011 78.73999 2012 80.02999 2013 80.6188 2014 80.99582 2015 83.94014 2016 84.32333 2017 87.93559