Year	Percent
1964-01-01	99.245600000000000
1965-01-01	95.824200000000000
1966-01-01	94.910900000000000
1967-01-01	98.416800000000000
1968-01-01	99.893200000000000
1969-01-01	97.487800000000000
1970-01-01	85.480200000000000
1971-01-01	74.610000000000000
1972-01-01	70.421800000000000
1973-01-01	71.666500000000000
1974-01-01	70.560500000000000
1975-01-01	63.601900000000000
1976-01-01	61.626700000000000
1977-01-01	64.952600000000000
1978-01-01	67.503500000000000
1979-01-01	68.164600000000000
1980-01-01	67.976900000000000
1981-01-01	66.932300000000000
1982-01-01	66.721400000000000
1983-01-01	53.207300000000000
1984-01-01	40.586400000000000
1985-01-01	36.269700000000000
1986-01-01	32.213700000000000
1987-01-01	31.468500000000000
1988-01-01	30.080100000000000
1989-01-01	25.027400000000000
1990-01-01	21.727200000000000
1991-01-01	24.424500000000000
1992-01-01	29.331100000000000
1993-01-01	30.601300000000000
1994-01-01	32.134700000000000
1995-01-01	36.318000000000005
1996-01-01	35.841800000000000
1997-01-01	37.182800000000000
1998-01-01	38.158900000000000
1999-01-01	34.162000000000000
2000-01-01	28.700200000000000
2001-01-01	30.686600000000000
2002-01-01	39.552600000000000
2003-01-01	47.658600000000000
2004-01-01	54.922900000000000
2005-01-01	66.825900000000000
2006-01-01	76.934500000000000
2007-01-01	78.658600000000000
2008-01-01	75.955800000000000
2009-01-01	75.420600000000000
2010-01-01	75.379200000000000
2011-01-01	70.398100000000000
2012-01-01	63.678000000000004
2013-01-01	59.870200000000000
2014-01-01	58.518000000000000
2015-01-01	59.084600000000000