Year	Percent
1967-01-01	99.4169
1968-01-01	95.1441
1969-01-01	89.2456
1970-01-01	85.1243
1971-01-01	84.0013
1972-01-01	83.1564
1973-01-01	82.2328
1974-01-01	84.5940
1975-01-01	84.3509
1976-01-01	79.4188
1977-01-01	76.7739
1978-01-01	74.4375
1979-01-01	71.6139
1980-01-01	69.9391
1981-01-01	64.9146
1982-01-01	60.6333
1983-01-01	57.1254
1984-01-01	53.8310
1985-01-01	56.7290
1986-01-01	59.2246
1987-01-01	58.5075
1988-01-01	58.9772
1989-01-01	63.9728
1990-01-01	69.3859
1991-01-01	64.3175
1992-01-01	53.6722
1993-01-01	47.4151
1994-01-01	44.5832
1995-01-01	44.9734
1996-01-01	48.0013
1997-01-01	49.3763
1998-01-01	53.3937
1999-01-01	55.0398
2000-01-01	54.7203
2001-01-01	54.6739
2002-01-01	55.1610
2003-01-01	54.2566
2004-01-01	51.7825
2005-01-01	49.1029
2006-01-01	48.0878
2007-01-01	48.4252
2008-01-01	48.5445
2009-01-01	46.2956
2010-01-01	46.3506
2011-01-01	50.5697
2012-01-01	51.5394
2013-01-01	48.6099
2014-01-01	47.0969
2015-01-01	47.7580