Year Percent 1995-01-01 24 1996-01-01 25 1997-01-01 26 1998-01-01 26 1999-01-01 29 2000-01-01 30 2001-01-01 29 2002-01-01 32 2003-01-01 29 2004-01-01 30 2005-01-01 33 2006-01-01 35 2007-01-01 46 2008-01-01 48 2009-01-01 50 2010-01-01 47 2011-01-01 48 2012-01-01 48 2013-01-01 48