Year	Percent
1974-01-01	94.062200000000000
1975-01-01	84.686600000000000
1976-01-01	78.307300000000000
1977-01-01	70.727000000000000
1978-01-01	60.606400000000000
1979-01-01	51.074800000000000
1980-01-01	45.756800000000000
1981-01-01	42.168000000000000
1982-01-01	39.979900000000000
1983-01-01	37.660800000000000
1984-01-01	36.194300000000000
1985-01-01	36.653600000000000
1986-01-01	37.205999999999996
1987-01-01	37.119900000000000
1988-01-01	35.972700000000000
1989-01-01	36.081300000000000
1990-01-01	39.764800000000000
1991-01-01	43.304400000000000
1992-01-01	44.824000000000000
1993-01-01	49.347600000000000
1994-01-01	54.698100000000000
1995-01-01	57.189200000000000
1996-01-01	57.473600000000000
1997-01-01	60.431400000000000
1998-01-01	59.775000000000000
1999-01-01	56.617000000000000
2000-01-01	57.047400000000000
2001-01-01	59.355800000000000
2002-01-01	61.047700000000000
2003-01-01	64.112000000000000
2004-01-01	69.878200000000000
2005-01-01	74.228000000000010
2006-01-01	76.720600000000000
2007-01-01	80.076300000000000
2008-01-01	83.698900000000000
2009-01-01	85.442500000000000
2010-01-01	85.488100000000000
2011-01-01	85.353000000000000
2012-01-01	85.744000000000000
2013-01-01	86.697600000000000
2014-01-01	83.865100000000000
2015-01-01	79.830000000000000
2016-01-01	79.046800000000000