Year Percent 1995-01-01 4.8336200000000000 1996-01-01 3.7180100000000000 1997-01-01 3.3134500000000000 1998-01-01 3.9058699999999997 1999-01-01 5.1940599999999995 2000-01-01 6.4198200000000000 2001-01-01 7.0277600000000010 2002-01-01 7.3980900000000000 2003-01-01 7.7819600000000010 2004-01-01 8.4566800000000000 2005-01-01 11.3221000000000000 2006-01-01 15.9325000000000000 2007-01-01 21.7942000000000000 2008-01-01 29.6485000000000000 2009-01-01 32.2327000000000000 2010-01-01 29.0761000000000000 2011-01-01 30.2839000000000000 2012-01-01 32.4834000000000000 2013-01-01 36.3547000000000000 2014-01-01 40.9212000000000000 2015-01-01 45.8767000000000000 2016-01-01 51.4479000000000000