Year Percent 1991-01-01 4.4510300000000000 1992-01-01 4.7980500000000000 1993-01-01 3.2914199999999996 1994-01-01 3.2242599999999997 1995-01-01 4.4516000000000000 1996-01-01 6.7176300000000010 1997-01-01 6.9027899999999995 1998-01-01 9.5485300000000000 1999-01-01 11.2321000000000000 2000-01-01 10.7395000000000000 2001-01-01 12.5761000000000000 2002-01-01 14.6747000000000000 2003-01-01 17.1557000000000000 2004-01-01 19.2163000000000000 2005-01-01 20.7563000000000000 2006-01-01 23.6601000000000000 2007-01-01 29.4587000000000000 2008-01-01 34.4748000000000000 2009-01-01 36.3223000000000000 2010-01-01 32.2212000000000000 2011-01-01 31.7192000000000000 2012-01-01 34.6408000000000000 2013-01-01 36.4899000000000000 2014-01-01 34.9292000000000000 2015-01-01 31.8073000000000000 2016-01-01 27.6011000000000000