Year Percent 1985 2.1777 1986 1.95079 1987 -4.23069 1988 -4.8164 1989 10.93156 1990 3.69613 1991 1.40105 1992 2.69272 1993 3.14253 1994 5.4872 1995 4.57067 1996 4.65789 1997 4.77251 1998 2.0653 1999 5.45311 2000 4.05139 2001 4.08613 2002 4.32522 2003 4.50093 2004 4.76271 2005 5.44305 2006 6.84904 2007 5.78062 2008 6.00051 2009 5.75705 2010 6.88955 2011 6.55095 2012 6.65064 2013 6.70581 2014 6.27279 2015 5.85998 2016 5.52843 2017 5.33713