Year	Percent
1960-01-01	22.2291000000000000
1961-01-01	21.0618000000000000
1962-01-01	20.3309000000000000
1963-01-01	20.7583000000000000
1964-01-01	21.6593000000000000
1965-01-01	20.6481000000000000
1966-01-01	18.7546000000000000
1967-01-01	18.6729000000000000
1968-01-01	18.0780000000000000
1969-01-01	16.6110000000000000
1970-01-01	11.9079000000000000
1971-01-01	11.9999000000000000
1972-01-01	11.8319000000000000
1973-01-01	12.2832000000000000
1974-01-01	11.6377000000000000
1975-01-01	12.7581000000000000
1976-01-01	15.4184000000000000
1977-01-01	17.1747000000000000
1978-01-01	17.1747000000000000
1979-01-01	14.6919000000000000
1980-01-01	11.5398000000000000
1981-01-01	16.1829000000000000
1982-01-01	23.0291000000000000
1983-01-01	29.4549000000000000
1984-01-01	29.4549000000000000
1985-01-01	29.4549000000000000
1986-01-01	29.4549000000000000
1987-01-01	29.4549000000000000
1988-01-01	29.4549000000000000
1989-01-01	14.7674000000000000
1990-01-01	15.1498000000000000
1991-01-01	15.7944000000000000
1992-01-01	15.7405000000000000
1993-01-01	12.2863000000000000
1994-01-01	7.7880199999999995
1995-01-01	7.7404699999999990
1996-01-01	7.3252900000000000
1997-01-01	7.0790700000000000
1998-01-01	9.2881700000000000
1999-01-01	9.2199700000000000
2000-01-01	5.6903200000000000
2001-01-01	5.0470500000000000
2002-01-01	3.8190900000000000
2003-01-01	3.2992800000000004
2004-01-01	3.0049099999999997
2005-01-01	2.3283800000000000
2006-01-01	1.9615000000000000
2007-01-01	2.4144799999999997
2008-01-01	2.7957500000000000
2009-01-01	4.3847200000000000
2010-01-01	4.4078599999999994
2011-01-01	5.5119099999999990
2012-01-01	7.9337800000000005
2013-01-01	10.3228000000000000
2014-01-01	12.3902000000000000
2015-01-01	20.5954000000000000