Year Percent 1996 2.28206 1997 2.21591 1998 2.56571 1999 2.40238 2000 2.6006 2001 2.1323 2002 2.12624 2003 2.27847 2004 2.09617 2005 2.1669 2006 2.055 2007 1.52209 2008 1.2908 2009 1.5152 2010 2.33571 2011 2.55156 2012 2.86554 2013 3.44848 2014 3.38907 2015 3.01066 2016 2.70442 2017 2.0511