Year	Percent
1960-01-01	3.4985500000000000
1961-01-01	7.3467199999999995
1962-01-01	8.1917000000000000
1963-01-01	8.4981000000000000
1964-01-01	5.3479700000000000
1965-01-01	5.3928500000000000
1966-01-01	5.7839700000000000
1967-01-01	7.0668399999999990
1968-01-01	16.2863000000000000
1969-01-01	8.7939800000000000
1970-01-01	13.0340000000000000
1971-01-01	10.3620000000000000
1972-01-01	9.3928800000000000
1973-01-01	9.2021300000000000
1974-01-01	10.2327000000000000
1975-01-01	12.0027000000000000
1976-01-01	13.0623000000000000
1977-01-01	12.2092000000000000
1978-01-01	14.2550000000000000
1979-01-01	21.2911000000000000
1980-01-01	22.7692000000000000
1981-01-01	13.6918000000000000
1982-01-01	10.5659999999999990
1983-01-01	10.5659999999999990
1984-01-01	10.6639000000000000
1985-01-01	13.2047000000000000
1986-01-01	16.5950000000000000
1987-01-01	18.1955000000000000
1988-01-01	11.8814000000000000
1989-01-01	6.3594700000000000
1990-01-01	6.1564100000000000
1991-01-01	6.3521600000000000
1992-01-01	6.3121599999999995
1993-01-01	5.3057300000000005
1994-01-01	3.4831300000000005
1995-01-01	3.1806000000000000
1996-01-01	3.1909099999999997
1997-01-01	2.9855300000000000
1998-01-01	2.8605700000000000
1999-01-01	3.1133300000000000
2000-01-01	2.9994200000000000
2001-01-01	2.8250200000000000
2002-01-01	3.2275600000000000
2003-01-01	3.4815500000000000
2004-01-01	2.6660100000000000
2005-01-01	2.4350600000000000
2006-01-01	2.4979700000000000
2007-01-01	2.2079500000000000
2008-01-01	2.6403200000000000
2009-01-01	3.6893800000000003
2010-01-01	3.6752800000000003
2011-01-01	3.9103800000000004
2012-01-01	4.9946900000000000
2013-01-01	5.8226800000000000
2014-01-01	6.5944199999999995
2015-01-01	8.3769400000000000