Year	Percent
1964-01-01	89.7538
1965-01-01	88.0235
1966-01-01	85.2253
1967-01-01	86.3660
1968-01-01	82.9969
1969-01-01	75.9249
1970-01-01	68.2219
1971-01-01	61.9658
1972-01-01	61.2949
1973-01-01	67.0485
1974-01-01	69.7448
1975-01-01	81.5904
1976-01-01	85.4439
1977-01-01	77.5093
1978-01-01	70.6773
1979-01-01	71.4399
1980-01-01	67.6461
1981-01-01	61.8375
1982-01-01	59.7459
1983-01-01	61.5000
1984-01-01	63.0900
1985-01-01	53.0396
1986-01-01	41.1171
1987-01-01	37.0201
1988-01-01	36.3538
1989-01-01	37.3502
1990-01-01	42.1373
1991-01-01	41.4059
1992-01-01	42.3966
1993-01-01	42.1707
1994-01-01	41.3883
1995-01-01	44.7489
1996-01-01	46.6575
1997-01-01	46.2713
1998-01-01	47.3197
1999-01-01	48.3090
2000-01-01	47.5733
2001-01-01	44.9674
2002-01-01	42.2914
2003-01-01	39.0323
2004-01-01	36.0266
2005-01-01	32.7513
2006-01-01	30.1278
2007-01-01	30.7675
2008-01-01	31.2951
2009-01-01	31.1647
2010-01-01	32.4629
2011-01-01	35.2200
2012-01-01	36.8603
2013-01-01	38.0290
2014-01-01	39.1594
2015-01-01	39.9483
2016-01-01	39.9146