Year	Percent
1973-01-01	15.099100000000000
1974-01-01	14.160000000000000
1975-01-01	13.935700000000000
1976-01-01	14.444500000000000
1977-01-01	15.009000000000000
1978-01-01	16.057000000000002
1979-01-01	15.824600000000000
1980-01-01	17.304400000000000
1981-01-01	18.649900000000000
1982-01-01	17.425900000000000
1983-01-01	16.073300000000000
1984-01-01	16.488200000000000
1985-01-01	17.661100000000000
1986-01-01	18.442600000000000
1987-01-01	16.683600000000000
1988-01-01	15.476200000000000
1989-01-01	14.671000000000000
1990-01-01	16.048500000000000
1991-01-01	17.057100000000000
1992-01-01	16.136100000000000
1993-01-01	16.687800000000000
1994-01-01	16.174800000000000
1995-01-01	12.713900000000000
1996-01-01	10.905900000000000
1997-01-01	10.768700000000000
1998-01-01	10.771900000000000
1999-01-01	9.899160000000000
2000-01-01	10.074800000000000
2001-01-01	11.017300000000000
2002-01-01	13.551500000000000
2003-01-01	12.720600000000000
2004-01-01	12.510900000000000
2005-01-01	11.196600000000000
2006-01-01	11.084100000000000
2007-01-01	11.580600000000000
2008-01-01	12.119000000000002
2009-01-01	13.804500000000000
2010-01-01	13.965900000000000
2011-01-01	13.896600000000000
2012-01-01	14.214700000000000
2013-01-01	14.874900000000000
2014-01-01	15.015500000000000
2015-01-01	15.345400000000000
2016-01-01	15.600200000000000