Year	Percent
1998-01-01	0.41
1999-01-01	1.79
2000-01-01	3.80
2001-01-01	5.72
2002-01-01	7.69
2003-01-01	10.60
2004-01-01	14.08
2005-01-01	17.25
2006-01-01	18.84
2007-01-01	20.29
2008-01-01	21.29
2009-01-01	24.96
2010-01-01	26.73
2011-01-01	26.88
2012-01-01	28.98
2013-01-01	30.56
2014-01-01	32.31
2015-01-01	33.34
2016-01-01	34.93