Year Percent 1989 0.61263 1990 3.69235 1991 -1.23953 1992 -2.75205 1993 -2.13034 1994 -1.64465 1995 0.49943 1996 1.66343 1997 0.83746 1998 1.10603 1999 2.20248 2000 2.21896 2001 3.17055 2002 4.23581 2003 3.88994 2004 4.73025 2005 4.99335 2006 1.51229 2007 5.13563 2008 2.28708 2009 2.09847 2010 3.05497 2011 4.57042 2012 1.90735 2013 3.97761 2014 3.69775 2015 3.69917 2016 3.71875 2017 3.85953