Year	Percent
1960-01-01	18.7678
1961-01-01	18.3975
1962-01-01	31.6598
1963-01-01	44.6902
1964-01-01	47.2894
1965-01-01	50.6188
1966-01-01	53.5417
1967-01-01	55.9675
1968-01-01	58.8376
1969-01-01	60.5760
1970-01-01	59.6208
1971-01-01	64.2735
1972-01-01	69.4353
1973-01-01	69.4820
1974-01-01	63.2702
1975-01-01	63.9651
1976-01-01	63.1774
1977-01-01	63.3860
1978-01-01	66.1018
1979-01-01	65.4986
1980-01-01	61.8016
1981-01-01	57.2220
1982-01-01	55.6754
1983-01-01	56.0277
1984-01-01	55.2254
1985-01-01	54.8602
1986-01-01	54.0659
1987-01-01	53.3691
1988-01-01	51.9479
1989-01-01	51.5623
1990-01-01	50.6949
1991-01-01	51.1447
1992-01-01	51.9076
1993-01-01	53.5152
1994-01-01	52.6352
1995-01-01	49.5607
1996-01-01	47.6459
1997-01-01	44.1344
1998-01-01	40.6017
1999-01-01	45.6531
2000-01-01	49.0159
2001-01-01	50.2003
2002-01-01	51.5480
2003-01-01	54.8523
2004-01-01	55.8722
2005-01-01	56.4220
2006-01-01	57.0003
2007-01-01	61.7193
2008-01-01	68.9636
2009-01-01	74.3448
2010-01-01	73.7009
2011-01-01	71.1222
2012-01-01	73.3265
2013-01-01	75.6101
2014-01-01	76.6775
2015-01-01	78.0295
2016-01-01	79.6528