Year	Percent
1987-01-01	7.3625000000000000
1988-01-01	6.0083300000000000
1989-01-01	4.3341699999999990
1990-01-01	3.0650000000000000
1991-01-01	2.2366700000000000
1992-01-01	2.2266700000000000
1993-01-01	3.0050000000000000
1994-01-01	3.8716699999999995
1995-01-01	2.7966700000000000
1996-01-01	2.8583300000000000
1997-01-01	2.8516700000000000
1998-01-01	3.6208300000000000
1999-01-01	4.4391700000000000
2000-01-01	4.3108300000000000
2001-01-01	3.7525000000000000
2002-01-01	3.3233300000000003
2003-01-01	3.2341700000000000
2004-01-01	3.0458300000000000
2005-01-01	2.9508300000000000
2006-01-01	3.3366700000000000
2007-01-01	3.2433300000000000
2008-01-01	2.9541700000000000
2009-01-01	3.0025000000000000
2010-01-01	2.4975000000000000
2011-01-01	2.0041700000000002
2012-01-01	1.8050000000000000
2013-01-01	1.6425000000000000
2014-01-01	1.5387899999999999
2015-01-01	1.4508299999999998
2016-01-01	1.5162900000000000