Year	Percent
1989-01-01	1.42
1990-01-01	1.34
1991-01-01	1.63
1992-01-01	1.73
1993-01-01	2.31
1994-01-01	2.87
1995-01-01	2.89
1996-01-01	3.50
1997-01-01	3.63
1998-01-01	3.81
1999-01-01	4.50
2000-01-01	4.93
2001-01-01	4.92
2002-01-01	4.47
2003-01-01	4.73
2004-01-01	5.69
2005-01-01	6.37
2006-01-01	7.00
2007-01-01	7.64
2008-01-01	7.88
2009-01-01	9.11
2010-01-01	8.91
2011-01-01	8.36
2012-01-01	8.09
2013-01-01	7.84
2014-01-01	7.57
2015-01-01	7.03
2016-01-01	7.50