Year Percent 1985 1.27625 1986 1.26918 1987 1.45626 1988 1.22107 1989 1.10818 1990 0.91492 1991 0.87112 1992 0.97318 1993 1.00196 1994 1.02406 1995 0.84236 1996 0.87481 1997 0.82469 1998 0.73147 1999 0.68365 2000 0.62552 2001 0.66692 2002 0.63585 2003 0.63012 2004 0.67053 2005 0.82118 2006 0.6551 2007 0.62121 2008 0.62415 2009 0.69315 2010 0.67191 2011 0.58801 2012 0.54241 2013 0.53013 2014 0.50382 2015 0.50359 2016 0.54267 2017 0.53174