Year	Percent
1973-01-01	25.160300000000000
1974-01-01	27.365900000000000
1975-01-01	26.332400000000000
1976-01-01	26.530800000000000
1977-01-01	29.076400000000000
1978-01-01	34.374300000000000
1979-01-01	37.437000000000000
1980-01-01	36.309900000000000
1981-01-01	35.406000000000000
1982-01-01	35.179400000000000
1983-01-01	35.319400000000000
1984-01-01	32.633000000000000
1985-01-01	30.681800000000000
1986-01-01	28.338600000000000
1987-01-01	26.459800000000000
1988-01-01	29.213100000000000
1989-01-01	29.445800000000000
1990-01-01	28.772900000000000
1991-01-01	26.912200000000000
1992-01-01	27.425100000000000
1993-01-01	27.695400000000000
1994-01-01	22.905800000000000
1995-01-01	17.017100000000000
1996-01-01	18.142100000000000
1997-01-01	19.503000000000000
1998-01-01	18.462000000000000
1999-01-01	18.194900000000000
2000-01-01	19.556300000000000
2001-01-01	21.029200000000000
2002-01-01	20.836900000000000
2003-01-01	20.683500000000000
2004-01-01	21.876400000000000
2005-01-01	23.696300000000000
2006-01-01	25.912500000000000
2007-01-01	26.750500000000000
2008-01-01	27.624100000000000
2009-01-01	29.008300000000000
2010-01-01	30.066999999999997
2011-01-01	32.146500000000000
2012-01-01	34.117700000000000
2013-01-01	37.464600000000000
2014-01-01	39.592300000000000
2015-01-01	40.785200000000000
2016-01-01	42.155700000000000