Year	Percent
1997-01-01	19.999200000000000
1998-01-01	18.188100000000000
1999-01-01	16.558700000000000
2000-01-01	15.256200000000000
2001-01-01	13.717200000000000
2002-01-01	12.347200000000000
2003-01-01	10.519300000000000
2004-01-01	9.365580000000000
2005-01-01	6.493640000000000
2006-01-01	6.178890000000000
2007-01-01	6.806110000000000
2008-01-01	6.660089999999999
2009-01-01	6.462390000000000
2010-01-01	6.056369999999999
2011-01-01	5.687450000000000
2012-01-01	5.337840000000000
2013-01-01	5.080780000000000
2014-01-01	4.864690000000000
2015-01-01	4.524190000000000
2016-01-01	4.324330000000001
2017-01-01	4.281530000000000