Year Percent 1993 0.53007 1994 0.77379 1995 0.92597 1996 0.90669 1997 0.90277 1998 0.62486 1999 0.5113 2000 0.39514 2001 0.40259 2002 0.41985 2003 0.41638 2004 0.36098 2005 0.40023 2006 0.48263 2007 0.51619 2008 0.60854 2009 0.45789 2010 0.3155 2011 0.32739 2012 0.32767 2013 0.33449 2014 0.34529 2015 0.35394 2016 0.44 2017 0.42068