Year	Percent
1973-01-01	33.218500000000000
1974-01-01	31.548000000000002
1975-01-01	31.565500000000000
1976-01-01	32.986100000000000
1977-01-01	32.610100000000000
1978-01-01	30.814700000000000
1979-01-01	32.103900000000000
1980-01-01	33.893700000000000
1981-01-01	37.298900000000000
1982-01-01	44.156500000000000
1983-01-01	45.261800000000000
1984-01-01	41.674200000000000
1985-01-01	38.622200000000000
1986-01-01	40.532900000000000
1987-01-01	44.678200000000000
1988-01-01	47.044900000000000
1989-01-01	47.694400000000000
1990-01-01	34.551000000000000
1991-01-01	27.766500000000000
1992-01-01	24.217200000000000
1993-01-01	23.767900000000000
1994-01-01	26.652800000000000
1995-01-01	27.123600000000000
1996-01-01	30.897300000000000
1997-01-01	31.441600000000000
1998-01-01	32.717100000000000
1999-01-01	35.173100000000000
2000-01-01	37.326100000000000
2001-01-01	40.122000000000000
2002-01-01	41.118100000000000
2003-01-01	42.393400000000000
2004-01-01	42.413500000000000
2005-01-01	42.126600000000000
2006-01-01	42.372800000000000
2007-01-01	41.523000000000000
2008-01-01	45.306000000000004
2009-01-01	44.718600000000000
2010-01-01	42.880100000000000
2011-01-01	40.446600000000000
2012-01-01	41.970000000000000
2013-01-01	42.750300000000000
2014-01-01	41.413700000000000
2015-01-01	39.777900000000000
2016-01-01	41.828900000000000