Year	Percent
1973-01-01	26.170400000000000
1974-01-01	27.687900000000000
1975-01-01	29.673000000000002
1976-01-01	30.834000000000000
1977-01-01	31.886200000000000
1978-01-01	34.582000000000000
1979-01-01	32.448700000000000
1980-01-01	32.144600000000000
1981-01-01	34.734300000000000
1982-01-01	37.555200000000000
1983-01-01	37.455100000000000
1984-01-01	33.134100000000000
1985-01-01	30.717700000000000
1986-01-01	32.295800000000000
1987-01-01	32.625600000000000
1988-01-01	29.010200000000000
1989-01-01	29.098100000000000
1990-01-01	26.498800000000000
1991-01-01	16.397800000000000
1992-01-01	17.062100000000000
1993-01-01	18.605000000000000
1994-01-01	18.916300000000000
1995-01-01	19.116300000000000
1996-01-01	20.167900000000000
1997-01-01	21.910300000000000
1998-01-01	22.685900000000000
1999-01-01	25.430400000000000
2000-01-01	27.646200000000000
2001-01-01	31.924500000000000
2002-01-01	33.528100000000000
2003-01-01	31.270800000000000
2004-01-01	25.822000000000000
2005-01-01	20.143100000000000
2006-01-01	19.461000000000000
2007-01-01	19.503200000000000
2008-01-01	21.516900000000000
2009-01-01	23.447900000000000
2010-01-01	23.811500000000000
2011-01-01	24.314800000000000
2012-01-01	24.721400000000000
2013-01-01	26.114100000000000
2014-01-01	27.118400000000000
2015-01-01	28.539600000000000
2016-01-01	30.343300000000000