Year Percent 1996 3.5714 1997 2.1583 1998 2.7701 1999 3.6794 2000 4.2254 2001 4.182 2002 4.0915 2003 4.3478 2004 3.5632 2005 3.537 2006 3.4688 2007 2.7548 2008 2.592 2009 2.27 2010 1.91 2011 1.86 2012 1.28 2013 1.35 2014 0.87 2015 1.5 2016 1.4379 2017 1.4277