Year Percent 1995 8.27 1996 7.61 1997 7.1 1998 6.23 1999 6.26 2000 5.45 2001 4.08 2002 3.31 2003 2.33 2004 1.85 2005 1.95 2006 1.91 2007 1.79 2008 1.58 2009 1.67 2010 2.5 2011 3.18 2012 3.46 2013 3.29 2014 2.7 2015 2.4 2016 2 2017 1.7 2018 1.7