Year	Percent
1995-01-01	15
1996-01-01	15
1997-01-01	15
1998-01-01	17
1999-01-01	20
2000-01-01	20
2001-01-01	20
2002-01-01	20
2003-01-01	20
2004-01-01	20
2005-01-01	23
2006-01-01	22
2007-01-01	23
2008-01-01	20
2009-01-01	22
2010-01-01	22
2011-01-01	22
2012-01-01	20
2013-01-01	21