Year Percent 1994 18.30408 1995 18.74552 1996 19.29855 1997 16.93307 1998 16.32998 1999 16.22535 2000 16.51051 2001 18.71887 2002 19.84501 2003 20.73053 2004 21.65811 2005 20.89706 2006 22.18771 2007 21.47237 2008 22.40083 2009 20.5648 2010 22.32388 2011 22.20844 2012 18.9765 2013 19.06987