Year	Percent
1970-01-01	4.9003900000000000
1971-01-01	4.1256900000000005
1972-01-01	3.5376199999999995
1973-01-01	32.6471000000000000
1974-01-01	29.9499000000000000
1975-01-01	4.1793800000000000
1976-01-01	7.0673300000000000
1977-01-01	12.7707000000000000
1978-01-01	19.5565000000000000
1979-01-01	20.1145000000000000
1980-01-01	19.0254000000000000
1981-01-01	21.2774000000000000
1982-01-01	31.2691000000000000
1983-01-01	44.2687000000000000
1984-01-01	52.4118000000000000
1985-01-01	61.6966000000000000
1986-01-01	73.2666000000000000
1987-01-01	74.2089000000000000
1988-01-01	73.8041000000000000
1989-01-01	70.1892000000000000
1990-01-01	56.7052000000000000
1991-01-01	50.8561000000000000
1992-01-01	49.6130000000000000
1993-01-01	53.4012000000000000
1994-01-01	55.0400000000000000
1995-01-01	55.7467000000000000
1996-01-01	51.1260000000000050
1997-01-01	49.8009000000000000
1998-01-01	60.4365000000000000
1999-01-01	58.4647000000000000
2000-01-01	51.3776000000000000
2001-01-01	54.5139999999999960
2002-01-01	55.8503000000000000
2003-01-01	52.8318000000000000
2004-01-01	49.9651000000000000
2005-01-01	46.5413000000000000
2006-01-01	45.4969000000000000
2007-01-01	45.8163000000000000
2008-01-01	45.3570000000000000
2009-01-01	61.6445000000000000
2010-01-01	52.8769999999999950
2011-01-01	45.5865000000000000
2012-01-01	46.3875000000000000
2013-01-01	47.8908000000000000
2014-01-01	49.1739000000000000
2015-01-01	62.8454000000000000
2016-01-01	68.4963000000000000