Year	Percent
1960-01-01	29.8416
1961-01-01	27.9395
1962-01-01	29.7802
1963-01-01	30.9768
1964-01-01	32.1511
1965-01-01	33.0947
1966-01-01	35.6896
1967-01-01	42.2252
1968-01-01	45.9954
1969-01-01	46.9347
1970-01-01	40.9297
1971-01-01	41.6371
1972-01-01	34.8097
1973-01-01	28.2493
1974-01-01	26.0901
1975-01-01	25.1414
1976-01-01	27.1114
1977-01-01	27.1156
1978-01-01	22.9861
1979-01-01	15.6596
1980-01-01	13.3466
1981-01-01	35.0506
1982-01-01	57.0431
1983-01-01	57.0366
1984-01-01	59.5048
1985-01-01	66.0846
1986-01-01	61.3971
1987-01-01	60.5134
1988-01-01	60.7080
1989-01-01	61.4183
1990-01-01	58.5073
1991-01-01	54.6411
1992-01-01	54.6284
1993-01-01	58.9026
1994-01-01	59.5158
1995-01-01	61.0699
1996-01-01	65.9990
1997-01-01	70.2183
1998-01-01	72.3578
1999-01-01	77.5708
2000-01-01	78.1539
2001-01-01	83.7519
2002-01-01	88.2501
2003-01-01	89.1846
2004-01-01	86.2607
2005-01-01	87.5692
2006-01-01	89.0259
2007-01-01	88.6398
2008-01-01	93.7121
2009-01-01	95.6338
2010-01-01	82.6548
2011-01-01	73.4744
2012-01-01	75.3788
2013-01-01	76.0312
2014-01-01	80.0446
2015-01-01	82.0077
2016-01-01	82.0959