Year	Percent
1973-01-01	22.643400000000000
1974-01-01	24.531200000000000
1975-01-01	24.475900000000000
1976-01-01	21.681700000000000
1977-01-01	21.211300000000000
1978-01-01	23.642600000000000
1979-01-01	24.485400000000000
1980-01-01	25.108600000000000
1981-01-01	26.940500000000000
1982-01-01	30.184000000000000
1983-01-01	32.459300000000000
1984-01-01	34.137900000000000
1985-01-01	39.878200000000000
1986-01-01	38.855600000000000
1987-01-01	28.677700000000000
1988-01-01	30.118800000000000
1989-01-01	31.357500000000000
1990-01-01	25.376600000000000
1991-01-01	18.417600000000000
1992-01-01	18.934400000000000
1993-01-01	20.706100000000000
1994-01-01	26.463400000000000
1995-01-01	32.432800000000000
1996-01-01	36.530300000000000
1997-01-01	39.122100000000000
1998-01-01	40.918000000000000
1999-01-01	42.910900000000000
2000-01-01	45.417900000000000
2001-01-01	45.642100000000000
2002-01-01	43.265200000000000
2003-01-01	42.708900000000000
2004-01-01	44.146800000000000
2005-01-01	43.974000000000000
2006-01-01	43.608000000000004
2007-01-01	43.452700000000000
2008-01-01	44.277700000000000
2009-01-01	45.306800000000000
2010-01-01	43.061200000000000
2011-01-01	41.342800000000000
2012-01-01	41.640200000000000
2013-01-01	42.960500000000000
2014-01-01	43.947900000000000
2015-01-01	44.105200000000000
2016-01-01	45.933200000000000