Year	Percent
1960-01-01	47.009100000000000
1961-01-01	44.663000000000004
1962-01-01	45.520600000000000
1963-01-01	44.833500000000000
1964-01-01	47.517100000000000
1965-01-01	58.499400000000000
1966-01-01	62.831100000000000
1967-01-01	65.080100000000000
1968-01-01	66.097200000000000
1969-01-01	69.964600000000000
1970-01-01	75.570600000000000
1971-01-01	71.471100000000000
1972-01-01	73.073800000000000
1973-01-01	78.557100000000000
1974-01-01	73.304800000000000
1975-01-01	69.774700000000000
1976-01-01	72.658200000000000
1977-01-01	78.646100000000000
1978-01-01	85.808300000000000
1979-01-01	84.430700000000000
1980-01-01	83.488999999999990
1981-01-01	84.269300000000000
1982-01-01	77.757500000000000
1983-01-01	76.943600000000000
1984-01-01	80.318100000000000
1985-01-01	78.406000000000000
1986-01-01	78.048600000000000
1987-01-01	79.959300000000000
1988-01-01	78.027900000000000
1989-01-01	75.340600000000000
1990-01-01	73.873900000000000
1991-01-01	78.730000000000000
1992-01-01	87.832000000000010
1993-01-01	86.841200000000000
1994-01-01	73.830800000000000
1995-01-01	70.058500000000000
1996-01-01	69.533400000000000
1997-01-01	69.402200000000000
1998-01-01	72.848200000000000
1999-01-01	74.840500000000000
2000-01-01	75.998100000000000
2001-01-01	74.149000000000000
2002-01-01	72.513200000000000
2003-01-01	74.029100000000000
2004-01-01	77.329100000000000
2005-01-01	78.588600000000000
2006-01-01	78.902400000000000
2007-01-01	81.750300000000000
2008-01-01	81.948300000000000
2009-01-01	67.912100000000000
2010-01-01	59.541700000000000
2011-01-01	61.497600000000000
2012-01-01	59.643700000000000
2013-01-01	56.757600000000000
2014-01-01	56.081400000000000
2015-01-01	56.973600000000000
2016-01-01	58.695800000000000