Year	Percent
1960-01-01	20.448800000000000
1961-01-01	20.981500000000000
1962-01-01	24.299500000000000
1963-01-01	23.351100000000000
1964-01-01	26.548300000000000
1965-01-01	26.655100000000000
1966-01-01	29.967100000000000
1967-01-01	33.096000000000000
1968-01-01	33.042000000000000
1969-01-01	33.748200000000000
1970-01-01	25.488100000000000
1971-01-01	23.887300000000000
1972-01-01	22.742900000000000
1973-01-01	25.531800000000000
1974-01-01	29.166999999999998
1975-01-01	32.443600000000000
1976-01-01	34.264700000000000
1977-01-01	33.969700000000000
1978-01-01	34.199400000000000
1979-01-01	32.444100000000000
1980-01-01	31.260400000000000
1981-01-01	33.929000000000000
1982-01-01	37.687800000000000
1983-01-01	37.687800000000000
1984-01-01	37.687800000000000
1985-01-01	37.687800000000000
1986-01-01	37.687800000000000
1987-01-01	44.804300000000000
1988-01-01	44.376100000000000
1989-01-01	47.825800000000000
1990-01-01	48.877600000000000
1991-01-01	47.630100000000000
1992-01-01	46.275300000000000
1993-01-01	47.644200000000000
1994-01-01	47.385400000000000
1995-01-01	47.974300000000000
1996-01-01	44.916000000000004
1997-01-01	43.340300000000000
1998-01-01	44.340900000000000
1999-01-01	44.262700000000000
2000-01-01	48.139200000000000
2001-01-01	51.820600000000000
2002-01-01	54.140200000000000
2003-01-01	53.097000000000000
2004-01-01	52.840600000000000
2005-01-01	53.215300000000000
2006-01-01	53.028400000000000
2007-01-01	52.514700000000000
2008-01-01	53.471200000000000
2009-01-01	56.087500000000000
2010-01-01	60.372100000000000
2011-01-01	68.291500000000000
2012-01-01	69.521300000000000
2013-01-01	70.411600000000000
2014-01-01	70.784200000000000
2015-01-01	73.013900000000000
2016-01-01	73.450900000000000