Year	Percent
1973-01-01	27.452800000000000
1974-01-01	24.320999999999998
1975-01-01	23.979800000000000
1976-01-01	26.666100000000000
1977-01-01	27.102800000000000
1978-01-01	24.959800000000000
1979-01-01	24.178600000000000
1980-01-01	23.338300000000000
1981-01-01	24.696400000000000
1982-01-01	27.592600000000000
1983-01-01	29.275400000000000
1984-01-01	26.705100000000000
1985-01-01	26.064400000000000
1986-01-01	31.469600000000000
1987-01-01	30.776400000000000
1988-01-01	29.622300000000000
1989-01-01	26.362300000000000
1990-01-01	25.959100000000000
1991-01-01	26.625300000000000
1992-01-01	29.986700000000000
1993-01-01	29.539400000000000
1994-01-01	33.789000000000000
1995-01-01	34.690400000000000
1996-01-01	24.524900000000000
1997-01-01	26.970000000000000
1998-01-01	31.599900000000000
1999-01-01	29.365400000000000
2000-01-01	27.905500000000000
2001-01-01	26.770900000000000
2002-01-01	25.264800000000000
2003-01-01	25.819900000000000
2004-01-01	24.433900000000000
2005-01-01	24.332500000000000
2006-01-01	25.784100000000000
2007-01-01	29.021500000000000
2008-01-01	30.118000000000002
2009-01-01	33.495400000000000
2010-01-01	33.541500000000000
2011-01-01	33.582800000000000
2012-01-01	35.118500000000000
2013-01-01	37.657500000000000
2014-01-01	38.566800000000000
2015-01-01	39.242000000000000
2016-01-01	39.934600000000000