Year Percent 1995-01-01 27 1996-01-01 25 1997-01-01 25 1998-01-01 25 1999-01-01 25 2000-01-01 27 2001-01-01 33 2002-01-01 30 2003-01-01 30 2004-01-01 31 2005-01-01 32 2006-01-01 33 2007-01-01 34 2008-01-01 34 2009-01-01 35 2010-01-01 40 2011-01-01 40 2012-01-01 42 2013-01-01 42