Year	Percent
1964-01-01	34.128400000000000
1965-01-01	34.194600000000000
1966-01-01	34.412100000000000
1967-01-01	34.864000000000004
1968-01-01	32.466300000000000
1969-01-01	31.515500000000000
1970-01-01	41.119100000000000
1971-01-01	50.441400000000000
1972-01-01	46.746700000000000
1973-01-01	43.095800000000000
1974-01-01	49.312000000000000
1975-01-01	59.983700000000000
1976-01-01	61.481000000000000
1977-01-01	65.744800000000000
1978-01-01	74.241700000000000
1979-01-01	73.685500000000000
1980-01-01	75.399600000000000
1981-01-01	79.049100000000000
1982-01-01	78.230800000000000
1983-01-01	73.360100000000000
1984-01-01	73.201300000000000
1985-01-01	78.459000000000000
1986-01-01	79.773000000000000
1987-01-01	74.593700000000000
1988-01-01	74.902100000000000
1989-01-01	74.304600000000000
1990-01-01	61.327900000000000
1991-01-01	48.934800000000000
1992-01-01	44.271300000000000
1993-01-01	40.895900000000000
1994-01-01	38.380600000000000
1995-01-01	48.808300000000000
1996-01-01	48.755100000000000
1997-01-01	51.755200000000000
1998-01-01	56.204500000000000
1999-01-01	57.227100000000000
2000-01-01	59.941400000000000
2001-01-01	64.061300000000000
2002-01-01	67.012500000000000
2003-01-01	70.112700000000000
2004-01-01	74.404900000000000
2005-01-01	78.830800000000000
2006-01-01	82.305100000000000
2007-01-01	85.766200000000000
2008-01-01	88.681400000000000
2009-01-01	88.874500000000000
2010-01-01	88.105000000000000
2011-01-01	91.421500000000000
2012-01-01	94.292100000000000
2013-01-01	95.347400000000000
2014-01-01	96.008100000000000
2015-01-01	96.404900000000000
2016-01-01	96.846400000000000