Year Percent 1995-01-01 4 1996-01-01 5 1997-01-01 5 1998-01-01 5 1999-01-01 5 2000-01-01 7 2001-01-01 7 2002-01-01 8 2003-01-01 8 2004-01-01 9 2005-01-01 10 2006-01-01 10 2007-01-01 11 2008-01-01 11 2009-01-01 11 2010-01-01 11 2011-01-01 11 2012-01-01 12 2013-01-01 11