Year	Percent
1975-01-01	26.5933
1976-01-01	25.6312
1977-01-01	22.5527
1978-01-01	19.5167
1979-01-01	23.5600
1980-01-01	22.2360
1981-01-01	25.0210
1982-01-01	26.2697
1983-01-01	27.4991
1984-01-01	27.1290
1985-01-01	26.3689
1986-01-01	23.7891
1987-01-01	21.9541
1988-01-01	23.7749
1989-01-01	29.7005
1990-01-01	34.0074
1991-01-01	37.1414
1992-01-01	39.8480
1993-01-01	41.6215
1994-01-01	41.7656
1995-01-01	44.2075
1996-01-01	44.4223
1997-01-01	45.5052
1998-01-01	45.3386
1999-01-01	46.1438
2000-01-01	48.4931
2001-01-01	48.7734
2002-01-01	48.4241
2003-01-01	45.9294
2004-01-01	44.0399
2005-01-01	47.2690
2006-01-01	48.1037
2007-01-01	47.8345
2008-01-01	48.0573
2009-01-01	47.1785
2010-01-01	51.1884
2011-01-01	54.4206
2012-01-01	58.5794
2013-01-01	57.2961
2014-01-01	54.5912
2015-01-01	52.1165
2016-01-01	47.0581