Year	Percent
1991-01-01	17.18
1992-01-01	13.76
1993-01-01	11.65
1994-01-01	14.54
1995-01-01	11.18
1996-01-01	12.50
1997-01-01	20.66
1998-01-01	7.04
1999-01-01	4.79
2000-01-01	5.37
2001-01-01	4.01
2002-01-01	4.31
2003-01-01	3.77
2004-01-01	3.27
2005-01-01	3.70
2006-01-01	4.50
2007-01-01	4.99
2008-01-01	3.27
2009-01-01	2.00
2010-01-01	2.50
2011-01-01	3.26
2012-01-01	2.75
2013-01-01	2.50
2014-01-01	1.99
2015-01-01	1.48
2016-01-01	1.22
2017-01-01	1.51