Year	Percent
1998-01-01	1.20
1999-01-01	2.10
2000-01-01	2.96
2001-01-01	3.73
2002-01-01	4.35
2003-01-01	5.22
2004-01-01	6.24
2005-01-01	7.63
2006-01-01	8.92
2007-01-01	10.86
2008-01-01	10.06
2009-01-01	12.95
2010-01-01	14.63
2011-01-01	3.77
2012-01-01	3.88
2013-01-01	3.94
2014-01-01	4.03
2015-01-01	4.06
2016-01-01	4.28