Year	Percent
1972-01-01	15.085200000000000
1973-01-01	16.038100000000000
1974-01-01	15.502000000000000
1975-01-01	15.559400000000000
1976-01-01	15.968700000000000
1977-01-01	18.316400000000000
1978-01-01	21.551800000000000
1979-01-01	17.274900000000000
1980-01-01	13.038600000000000
1981-01-01	14.546200000000000
1982-01-01	18.255700000000000
1983-01-01	21.744600000000000
1984-01-01	22.872800000000000
1985-01-01	23.826000000000000
1986-01-01	28.796500000000000
1987-01-01	27.021200000000000
1988-01-01	29.362300000000000
1989-01-01	28.303100000000000
1990-01-01	24.902400000000000
1991-01-01	27.608800000000000
1992-01-01	26.211900000000000
1993-01-01	26.953000000000003
1994-01-01	27.374400000000000
1995-01-01	27.471400000000000
1996-01-01	26.776100000000000
1997-01-01	30.117600000000000
1998-01-01	38.698200000000000
1999-01-01	36.681500000000000
2000-01-01	32.051100000000000
2001-01-01	33.839000000000000
2002-01-01	35.224900000000000
2003-01-01	34.189000000000000
2004-01-01	30.777100000000000
2005-01-01	27.675500000000000
2006-01-01	28.477300000000000
2007-01-01	32.573000000000000
2008-01-01	29.489500000000000
2009-01-01	41.063300000000000
2010-01-01	36.891800000000000
2011-01-01	35.691200000000000
2012-01-01	35.193600000000000
2013-01-01	37.318600000000000
2014-01-01	40.292800000000000
2015-01-01	52.761300000000000
2016-01-01	60.173400000000000