Year	Percent
1998-01-01	1.66
1999-01-01	2.01
2000-01-01	2.17
2001-01-01	2.37
2002-01-01	2.62
2003-01-01	3.05
2004-01-01	3.15
2005-01-01	3.56
2006-01-01	3.41
2007-01-01	3.43
2008-01-01	3.58
2009-01-01	3.88
2010-01-01	4.15
2011-01-01	4.26
2012-01-01	4.47
2013-01-01	5.27
2014-01-01	5.78
2015-01-01	6.43
2016-01-01	6.40