Year Percent 1988-01-01 0.8892920000000000 1989-01-01 0.7494560000000000 1990-01-01 0.6242660000000000 1991-01-01 0.6062590000000000 1992-01-01 0.5485080000000000 1993-01-01 0.5005330000000000 1994-01-01 0.6076890000000000 1995-01-01 0.3757650000000000 1996-01-01 0.2591890000000000 1997-01-01 0.4768970000000000 1998-01-01 0.6656760000000000 1999-01-01 0.9138400000000000 2000-01-01 1.1138299999999999 2001-01-01 1.2927000000000000 2002-01-01 0.9300620000000000 2003-01-01 0.5519440000000000 2004-01-01 0.7069060000000000 2005-01-01 1.1824700000000001 2006-01-01 1.4960799999999999 2007-01-01 1.5269000000000000 2008-01-01 1.2908200000000000 2009-01-01 1.4942700000000000 2010-01-01 1.6000200000000000 2011-01-01 1.6369799999999999 2012-01-01 2.3060900000000000 2013-01-01 3.2157800000000000 2014-01-01 4.6052500000000000 2015-01-01 4.9148800000000000 2016-01-01 5.5481099999999990