Year	Percent
1990-01-01	7.54
1991-01-01	7.54
1992-01-01	7.54
1993-01-01	7.54
1994-01-01	7.54
1995-01-01	7.54
1996-01-01	7.54
1997-01-01	7.54
1998-01-01	7.54
1999-01-01	7.54
2000-01-01	7.54
2001-01-01	7.54
2002-01-01	16.19
2003-01-01	17.08
2004-01-01	17.06
2005-01-01	17.21
2006-01-01	17.60
2007-01-01	17.81
2008-01-01	16.47
2009-01-01	20.19
2010-01-01	20.23
2011-01-01	19.56
2012-01-01	20.14
2013-01-01	20.87
2014-01-01	20.18
2015-01-01	20.65
2016-01-01	20.33