Year Percent 1993 21.86 1994 20.85 1995 25.42 1996 22.53 1997 20.21 1998 18.7 1999 19.21 2000 20.29 2002 16.91 2003 15.89 2004 16.1 2005 19.28 2006 19.6 2015 15.27 2016 15.7