Year Percent 1991-01-01 11.1709000000000000 1992-01-01 9.2190600000000000 1993-01-01 4.8524199999999995 1994-01-01 5.9957699999999990 1995-01-01 5.0670800000000010 1996-01-01 6.6798899999999990 1997-01-01 5.1651099999999990 1998-01-01 5.6146000000000000 1999-01-01 6.2232400000000005 2000-01-01 5.8503300000000005 2001-01-01 7.0308600000000006 2002-01-01 10.1912000000000000 2003-01-01 15.8684000000000000 2004-01-01 19.3659000000000000 2005-01-01 21.4120000000000000 2006-01-01 21.7983000000000000 2007-01-01 25.7474000000000000 2008-01-01 26.5246000000000000 2009-01-01 31.3409999999999980 2010-01-01 31.3085000000000000 2011-01-01 34.1098000000000000 2012-01-01 39.8714000000000000 2013-01-01 48.5215000000000000 2014-01-01 55.0831000000000000 2015-01-01 54.6631000000000000 2016-01-01 52.9421000000000000