Year Percent 1995-01-01 33 1996-01-01 39 1997-01-01 42 1998-01-01 48 1999-01-01 50 2000-01-01 59 2001-01-01 63 2002-01-01 63 2003-01-01 60 2004-01-01 57 2005-01-01 54 2006-01-01 54 2007-01-01 64 2008-01-01 67 2009-01-01 67 2010-01-01 67 2011-01-01 67 2012-01-01 69 2013-01-01 69