Year	Percent
1977-01-01	1.277500000000000
1978-01-01	5.384110000000000
1979-01-01	11.132800000000000
1980-01-01	17.167100000000000
1981-01-01	21.061900000000000
1982-01-01	22.287100000000000
1983-01-01	21.344300000000000
1984-01-01	22.925200000000000
1985-01-01	27.898900000000000
1986-01-01	32.590500000000000
1987-01-01	28.843400000000000
1988-01-01	31.268300000000000
1989-01-01	37.198600000000000
1990-01-01	24.868600000000000
1991-01-01	17.679800000000000
1992-01-01	15.485999999999999
1993-01-01	15.701900000000000
1994-01-01	14.358900000000000
1995-01-01	13.434700000000000
1996-01-01	13.989100000000000
1997-01-01	14.631500000000000
1998-01-01	15.339700000000000
1999-01-01	15.953900000000000
2000-01-01	18.375600000000000
2001-01-01	19.293800000000000
2002-01-01	19.413700000000000
2003-01-01	19.190100000000000
2004-01-01	18.150500000000000
2005-01-01	17.759600000000000
2006-01-01	21.553000000000000
2007-01-01	26.515100000000000
2008-01-01	29.886700000000000
2009-01-01	31.890500000000000
2010-01-01	27.584400000000000
2011-01-01	21.680300000000000
2012-01-01	20.959900000000000
2013-01-01	27.741100000000000
2014-01-01	35.430700000000000
2015-01-01	35.749900000000000
2016-01-01	36.667700000000000