Year	Percent
1970-01-01	64.0
1971-01-01	64.2
1972-01-01	64.2
1973-01-01	64.1
1974-01-01	64.9
1975-01-01	65.9
1976-01-01	66.0
1977-01-01	66.0
1978-01-01	66.1
1979-01-01	66.6
1980-01-01	66.9
1981-01-01	66.8
1982-01-01	66.8
1983-01-01	66.7
1984-01-01	66.6
1985-01-01	66.9
1986-01-01	67.0
1987-01-01	66.5
1988-01-01	66.9
1989-01-01	67.3
1990-01-01	67.4
1991-01-01	67.0
1992-01-01	65.8
1993-01-01	64.5
1994-01-01	63.7
1995-01-01	64.0
1996-01-01	63.9
1997-01-01	63.3
1998-01-01	62.9
1999-01-01	62.7
2000-01-01	63.7
2001-01-01	63.7
2002-01-01	63.9
2003-01-01	63.9
2004-01-01	63.6
2005-01-01	64.8
2006-01-01	64.9
2007-01-01	65.3
2008-01-01	65.3
2009-01-01	64.8
2010-01-01	64.7
2011-01-01	65.1
2012-01-01	65.2