Year	Percent
1986-01-01	18.3804147852011
1987-01-01	17.9712289172753
1988-01-01	18.6089843136550
1989-01-01	19.2455382052558
1990-01-01	19.0548110950960
1991-01-01	18.6579335030603
1992-01-01	18.7370519842670
1993-01-01	19.0299405590036
1994-01-01	18.7694222614893
1995-01-01	18.5166350025598
1996-01-01	17.8949041784848
1997-01-01	18.1616445985122
1998-01-01	18.5508389679466
1999-01-01	18.2537019234641
2000-01-01	17.9585204933512
2001-01-01	17.6615773387959
2002-01-01	17.3026298553550
2003-01-01	17.5987575663671
2004-01-01	17.1511870736614
2005-01-01	16.1703845798841
2006-01-01	16.0177428299108
2007-01-01	16.0201216648459
2008-01-01	15.8053285271856
2009-01-01	15.9867204807587
2010-01-01	16.2645471653924
2011-01-01	15.7519464099345
2012-01-01	16.1661576651096
2013-01-01	15.4560038418893
2014-01-01	14.6650702009289
2015-01-01	14.8448308276670
2016-01-01	13.5418185244924
2017-01-01	12.8163613390773