Year Percent 1989-01-01 2.6542500000000000 1990-01-01 2.5472099999999998 1991-01-01 2.3881200000000002 1992-01-01 2.2546900000000000 1993-01-01 2.7161500000000000 1994-01-01 2.9881200000000000 1995-01-01 3.1974000000000000 1996-01-01 3.4632099999999997 1997-01-01 3.2612200000000002 1998-01-01 2.7512300000000000 1999-01-01 2.5166000000000000 2000-01-01 2.7074200000000000 2001-01-01 2.7847600000000000 2002-01-01 2.6758200000000000 2003-01-01 2.7063700000000000 2004-01-01 2.3244000000000000 2005-01-01 2.2617400000000000 2006-01-01 2.9356700000000000 2007-01-01 2.9611600000000000 2008-01-01 2.6378000000000000 2009-01-01 2.6600900000000003 2010-01-01 2.9667400000000000 2011-01-01 5.0308699999999990 2012-01-01 5.8365599999999995 2013-01-01 5.8608300000000000 2014-01-01 7.6994000000000000 2015-01-01 9.7219300000000000 2016-01-01 9.6062800000000000