Year	Percent
1976-01-01	57.7940
1977-01-01	53.2933
1978-01-01	50.7693
1979-01-01	40.2720
1980-01-01	33.2205
1981-01-01	31.5317
1982-01-01	29.9026
1983-01-01	29.7235
1984-01-01	27.4133
1985-01-01	29.4261
1986-01-01	30.9203
1987-01-01	31.9319
1988-01-01	33.5750
1989-01-01	34.0070
1990-01-01	34.4743
1991-01-01	33.6042
1992-01-01	35.6679
1993-01-01	38.7222
1994-01-01	35.4403
1995-01-01	34.2693
1996-01-01	34.1136
1997-01-01	32.7748
1998-01-01	33.2931
1999-01-01	36.0684
2000-01-01	35.2788
2001-01-01	35.5149
2002-01-01	38.4051
2003-01-01	39.0141
2004-01-01	39.5123
2005-01-01	42.0702
2006-01-01	41.7205
2007-01-01	41.4921
2008-01-01	46.3250
2009-01-01	57.3159
2010-01-01	63.5592
2011-01-01	66.4278
2012-01-01	69.7420
2013-01-01	69.7351
2014-01-01	70.9455
2015-01-01	71.5412
2016-01-01	68.1984