Year	Percent
1979-01-01	54.5837375416667
1980-01-01	56.9549477416667
1981-01-01	57.0449812083333
1982-01-01	55.8736520250000
1983-01-01	54.6683661500000
1984-01-01	55.6437337916667
1985-01-01	56.9527572166667
1986-01-01	57.9259502000000
1987-01-01	57.6496268333333
1988-01-01	58.2598321416667
1989-01-01	60.6633413416667
1990-01-01	60.0525165583333
1991-01-01	55.8242827166667
1992-01-01	54.7633552250000
1993-01-01	54.3957719666667
1994-01-01	57.0509132250000
1995-01-01	59.2346932250000
1996-01-01	59.1827325416667
1997-01-01	57.6174377916667
1998-01-01	58.4536733250000
1999-01-01	59.5091620333333
2000-01-01	60.7636201500000
2001-01-01	60.5789986583333
2002-01-01	60.2174646416667
2003-01-01	61.2225051583333
2004-01-01	61.5643808500000
2005-01-01	62.3709961666667
2006-01-01	62.9029009666667
2007-01-01	63.2439153166667
2008-01-01	63.4995172333333
2009-01-01	60.7200333833333
2010-01-01	59.7144528416667
2011-01-01	60.1956827500000
2012-01-01	59.4647453166667
2013-01-01	58.7396170000000
2014-01-01	57.9922935333333
2015-01-01	58.7754912416667
2016-01-01	58.7932484083333
2017-01-01	58.7267480166667