Year	Percent
1975-01-01	39.5762
1976-01-01	40.7890
1977-01-01	42.5245
1978-01-01	43.4317
1979-01-01	42.1343
1980-01-01	42.5255
1981-01-01	50.6553
1982-01-01	38.3899
1983-01-01	39.2874
1984-01-01	49.4626
1985-01-01	53.8831
1986-01-01	70.9239
1987-01-01	67.9173
1988-01-01	58.7606
1989-01-01	58.5649
1990-01-01	53.0294
1991-01-01	53.3582
1992-01-01	57.4919
1993-01-01	55.5885
1994-01-01	54.2319
1995-01-01	55.1957
1996-01-01	55.3783
1997-01-01	57.1557
1998-01-01	66.5258
1999-01-01	67.1593
2000-01-01	60.4463
2001-01-01	60.4463
2002-01-01	60.4463
2003-01-01	60.4463
2004-01-01	57.8813
2005-01-01	53.4626
2006-01-01	54.5590
2007-01-01	59.9250
2008-01-01	63.8712
2009-01-01	80.0009
2010-01-01	77.7025
2011-01-01	73.5159
2012-01-01	72.3317
2013-01-01	72.5521
2014-01-01	75.4840
2015-01-01	84.9532