Year	Percent
1997-01-01	1.6657799999999998
1998-01-01	2.0518200000000000
1999-01-01	2.9770700000000000
2000-01-01	3.6922599999999997
2001-01-01	4.9279600000000000
2002-01-01	6.3017500000000000
2003-01-01	7.4368300000000005
2004-01-01	7.6762399999999990
2005-01-01	8.1279000000000000
2006-01-01	8.5967100000000000
2007-01-01	9.6994200000000000
2008-01-01	10.9288000000000000
2009-01-01	13.0423000000000000
2010-01-01	13.9279999999999990
2011-01-01	14.6600000000000000
2012-01-01	16.2107000000000000
2013-01-01	17.7232000000000000
2014-01-01	18.1448000000000000
2015-01-01	19.3949000000000000
2016-01-01	19.5305000000000000