Year Percent 1990-01-01 2.4828200000000002 1991-01-01 2.2828300000000000 1992-01-01 2.3656000000000000 1993-01-01 2.6742500000000000 1994-01-01 2.7645900000000000 1995-01-01 2.9789300000000000 1996-01-01 3.5517500000000000 1997-01-01 4.2150700000000000 1998-01-01 5.3855200000000000 1999-01-01 6.7977399999999990 2000-01-01 9.0278200000000000 2001-01-01 9.8794899999999990 2002-01-01 13.3314000000000000 2003-01-01 14.8799000000000000 2004-01-01 14.7508000000000000 2005-01-01 14.4560000000000000 2006-01-01 13.1951000000000000 2007-01-01 17.2444000000000000 2008-01-01 15.7040000000000000 2009-01-01 16.2177000000000000 2010-01-01 16.2118000000000000 2011-01-01 15.8092000000000000 2012-01-01 15.2946000000000000 2013-01-01 16.2165000000000000 2014-01-01 16.3372000000000000 2015-01-01 21.0971000000000000 2016-01-01 28.7705000000000000