Year Percent 1992 11.08137 1993 17.51733 1994 11.32416 1995 9.77396 1996 9.60235 1997 10.57243 1998 8.35867 1999 9.80582 2000 13.91016 2001 14.66206 2002 13.36924 2003 18.03875 2006 28.70997 2007 23.47918 2008 21.65182 2009 16.54029 2010 19.59312 2011 18.46699 2012 15.31214 2013 15.73121 2014 12.90163 2015 11.76281 2016 11.34885