Year	Percent
1960-01-01	22.978100000000000
1961-01-01	22.531400000000000
1962-01-01	22.490200000000000
1963-01-01	22.380000000000000
1964-01-01	21.968000000000004
1965-01-01	21.277100000000000
1966-01-01	23.406500000000000
1967-01-01	23.480800000000000
1968-01-01	23.204600000000000
1969-01-01	25.327400000000000
1970-01-01	18.436100000000000
1971-01-01	20.947100000000000
1972-01-01	23.008100000000000
1973-01-01	22.466800000000000
1974-01-01	21.730400000000000
1975-01-01	24.627800000000000
1976-01-01	27.674500000000000
1977-01-01	28.772900000000000
1978-01-01	35.194500000000000
1979-01-01	34.311000000000000
1980-01-01	30.618100000000000
1981-01-01	33.602900000000000
1982-01-01	38.728600000000000
1983-01-01	50.754600000000000
1984-01-01	55.503000000000000
1985-01-01	59.313000000000000
1986-01-01	60.903200000000000
1987-01-01	60.645300000000000
1988-01-01	60.674100000000000
1989-01-01	59.102400000000000
1990-01-01	53.836400000000000
1991-01-01	52.602400000000000
1992-01-01	51.510400000000000
1993-01-01	49.864900000000000
1994-01-01	48.410000000000000
1995-01-01	49.111200000000000
1996-01-01	49.692900000000000
1997-01-01	54.373800000000000
1998-01-01	58.600300000000000
1999-01-01	57.133999999999990
2000-01-01	51.002800000000000
2001-01-01	52.661500000000000
2002-01-01	54.522500000000000
2003-01-01	43.610500000000000
2004-01-01	39.888900000000000
2005-01-01	39.813000000000000
2006-01-01	42.239600000000000
2007-01-01	40.944800000000000
2008-01-01	36.481400000000000
2009-01-01	61.930200000000000
2010-01-01	57.810400000000000
2011-01-01	46.547700000000000
2012-01-01	52.223000000000000
2013-01-01	55.844300000000000
2014-01-01	58.878500000000000
2015-01-01	68.264100000000000
2016-01-01	74.739100000000000