Year	Percent
1980-01-01	8.569700000000000
1981-01-01	9.840030000000000
1982-01-01	12.784500000000000
1983-01-01	13.688700000000000
1984-01-01	15.707000000000000
1985-01-01	18.411900000000000
1986-01-01	20.159000000000002
1987-01-01	20.448700000000000
1988-01-01	23.136100000000000
1989-01-01	27.243100000000000
1990-01-01	34.717000000000000
1991-01-01	39.049000000000000
1992-01-01	39.180900000000000
1993-01-01	39.786400000000000
1994-01-01	41.441100000000000
1995-01-01	42.574900000000000
1996-01-01	44.598700000000000
1997-01-01	46.599400000000000
1998-01-01	45.965000000000000
1999-01-01	39.777300000000000
2000-01-01	40.252500000000000
2001-01-01	40.593900000000000
2002-01-01	37.946000000000000
2003-01-01	35.595900000000000
2004-01-01	34.113300000000000
2005-01-01	31.912300000000000
2006-01-01	30.094000000000000
2007-01-01	28.857600000000000
2008-01-01	28.163300000000000
2009-01-01	28.423100000000000
2010-01-01	27.513200000000000
2011-01-01	28.428800000000000
2012-01-01	31.611200000000000
2013-01-01	34.701900000000000
2014-01-01	35.723700000000000
2015-01-01	37.007000000000000
2016-01-01	38.054600000000000