Year Percent 1998 5.09026 1999 4.77584 2000 4.95526 2001 4.79689 2002 3.85738 2003 3.78746 2004 3.34241 2005 3.06495 2006 1.77822 2007 1.33676 2008 1.70104 2009 4.75462 2010 6.76056 2011 5.69636 2012 5.08321 2013 3.84691 2014 3.33376 2015 3.11669 2016 2.98622 2017 2.40477