Year	Percent
1973-01-01	25.880100000000000
1974-01-01	20.656200000000000
1975-01-01	18.656500000000000
1976-01-01	21.125900000000000
1977-01-01	23.473200000000000
1978-01-01	23.664600000000000
1979-01-01	23.846500000000000
1980-01-01	23.210100000000000
1981-01-01	23.078000000000003
1982-01-01	23.416999999999998
1983-01-01	25.466300000000000
1984-01-01	24.891500000000000
1985-01-01	25.018700000000000
1986-01-01	27.356600000000000
1987-01-01	29.225900000000000
1988-01-01	28.316900000000000
1989-01-01	26.652800000000000
1990-01-01	25.233400000000000
1991-01-01	24.078800000000000
1992-01-01	26.382600000000000
1993-01-01	29.540300000000000
1994-01-01	28.883800000000000
1995-01-01	27.914400000000000
1996-01-01	28.658100000000000
1997-01-01	29.911700000000000
1998-01-01	29.927300000000000
1999-01-01	28.100800000000000
2000-01-01	28.002000000000000
2001-01-01	27.780700000000000
2002-01-01	30.503500000000000
2003-01-01	33.384000000000000
2004-01-01	34.020100000000000
2005-01-01	34.959300000000000
2006-01-01	34.661200000000000
2007-01-01	36.373200000000000
2008-01-01	38.653200000000000
2009-01-01	35.231400000000000
2010-01-01	36.574400000000000
2011-01-01	33.704800000000000
2012-01-01	36.628900000000000
2013-01-01	36.883200000000000
2014-01-01	37.043900000000000
2015-01-01	39.899300000000000
2016-01-01	43.144300000000000