Year	Percent
1960-01-01	82.2055
1961-01-01	79.6415
1962-01-01	67.6744
1963-01-01	54.1431
1964-01-01	47.2287
1965-01-01	43.7631
1966-01-01	46.4217
1967-01-01	49.2637
1968-01-01	52.3245
1969-01-01	58.6829
1970-01-01	64.5060
1971-01-01	64.1697
1972-01-01	56.4518
1973-01-01	52.6460
1974-01-01	49.9637
1975-01-01	42.3066
1976-01-01	38.0780
1977-01-01	34.0339
1978-01-01	31.2002
1979-01-01	33.7374
1980-01-01	36.2715
1981-01-01	38.2367
1982-01-01	38.0024
1983-01-01	36.0144
1984-01-01	35.8600
1985-01-01	34.2714
1986-01-01	33.2548
1987-01-01	33.5628
1988-01-01	37.3131
1989-01-01	41.3519
1990-01-01	43.3023
1991-01-01	42.0022
1992-01-01	35.4713
1993-01-01	32.9662
1994-01-01	36.3311
1995-01-01	44.1207
1996-01-01	57.7000
1997-01-01	70.3010
1998-01-01	77.1149
1999-01-01	80.0031
2000-01-01	78.4695
2001-01-01	72.6323
2002-01-01	67.5573
2003-01-01	59.7376
2004-01-01	50.9091
2005-01-01	48.8064
2006-01-01	48.9735
2007-01-01	49.5340
2008-01-01	51.9076
2009-01-01	52.7435
2010-01-01	52.4225
2011-01-01	54.3602
2012-01-01	57.4031
2013-01-01	60.9967
2014-01-01	65.9974
2015-01-01	69.7096
2016-01-01	69.5915