Year	Percent
1980-01-01	57.589100000000000
1981-01-01	61.917300000000000
1982-01-01	43.994200000000000
1983-01-01	42.104900000000000
1984-01-01	39.677400000000000
1985-01-01	38.739300000000000
1986-01-01	38.629900000000000
1987-01-01	38.959700000000000
1988-01-01	32.285700000000000
1989-01-01	26.728200000000000
1990-01-01	28.039800000000000
1991-01-01	27.588900000000000
1992-01-01	27.158100000000000
1993-01-01	28.294000000000000
1994-01-01	26.802300000000000
1995-01-01	27.326700000000000
1996-01-01	28.997300000000000
1997-01-01	30.999600000000000
1998-01-01	34.236800000000000
1999-01-01	37.009800000000000
2000-01-01	38.806999999999995
2001-01-01	41.845500000000000
2002-01-01	42.513999999999996
2003-01-01	41.203800000000000
2004-01-01	40.015800000000000
2005-01-01	41.493600000000000
2006-01-01	43.798900000000000
2007-01-01	44.815800000000000
2008-01-01	48.389800000000000
2009-01-01	51.272900000000000
2010-01-01	52.127400000000000
2011-01-01	53.402500000000000
2012-01-01	55.702600000000000
2013-01-01	57.440400000000000
2014-01-01	59.445300000000000
2015-01-01	61.656000000000006
2016-01-01	64.727800000000000