Year Percent 1985-01-01 1.44491145083333 1986-01-01 1.26981405775000 1987-01-01 1.45810669758333 1988-01-01 1.35129045825000 1989-01-01 1.22233414658333 1990-01-01 1.09931768300000 1991-01-01 1.21171439775000 1992-01-01 1.43691450783333 1993-01-01 1.85082964383333 1994-01-01 2.40830425958333 1995-01-01 2.61521090733333 1996-01-01 2.86398602475000 1997-01-01 3.08329506150000 1998-01-01 2.85183207966667 1999-01-01 2.69697836850000 2000-01-01 2.40173669541667 2001-01-01 2.23061890008333 2002-01-01 2.49645951150000 2003-01-01 3.29831502491667 2004-01-01 3.70861576283333 2005-01-01 4.09184573533333 2006-01-01 4.23954106091667 2007-01-01 4.18061942625000 2008-01-01 4.15101674700000 2009-01-01 5.44645583375000 2010-01-01 5.79773965983333 2011-01-01 5.65499150283333 2012-01-01 6.07203147391667 2013-01-01 6.86666666666667 2014-01-01 7.13333333333333 2015-01-01 6.84166666666667 2016-01-01 6.41666666666667