Year	Percent of Total
1960-01-01	56.7553180497753
1961-01-01	56.4902307065940
1962-01-01	56.2975204116841
1963-01-01	56.1816135239540
1964-01-01	56.1449760219284
1965-01-01	56.1770995693123
1966-01-01	56.0517631531065
1967-01-01	56.0095496014379
1968-01-01	56.0223682802408
1969-01-01	56.0541131963219
1970-01-01	56.0893119150837
1971-01-01	56.1052985374296
1972-01-01	56.1378697198538
1973-01-01	56.1867833308922
1974-01-01	56.2662092163018
1975-01-01	56.3819862378080
1976-01-01	56.3455504318799
1977-01-01	56.3660199366774
1978-01-01	56.4121869899773
1979-01-01	56.4572241248886
1980-01-01	56.4957173184598
1981-01-01	56.4828561320838
1982-01-01	56.4815976364760
1983-01-01	56.4854115580027
1984-01-01	56.5034154607915
1985-01-01	56.5433282010133
1986-01-01	56.5275332111407
1987-01-01	56.5770780397609
1988-01-01	56.6624296071116
1989-01-01	56.7642505723965
1990-01-01	56.8862670757529
1991-01-01	56.9206411790528
1992-01-01	56.9660674002734
1993-01-01	57.0401310787965
1994-01-01	57.1718125232050
1995-01-01	57.3583490500977
1996-01-01	57.4365105379289
1997-01-01	57.5999309920777
1998-01-01	57.8195942722374
1999-01-01	58.0793468668455
2000-01-01	58.3583859856871
2001-01-01	58.6916782261006
2002-01-01	59.0467745535664
2003-01-01	59.4214012356191
2004-01-01	59.8260350284715
2005-01-01	60.2668004230364
2006-01-01	60.8990589639884
2007-01-01	61.5389683864074
2008-01-01	62.1488796070645
2009-01-01	62.6944467296892
2010-01-01	63.1609645436172
2011-01-01	63.4143985274552
2012-01-01	63.6477851452225
2013-01-01	63.8360428178141
2014-01-01	63.9815347419061
2015-01-01	64.1040935404755
2016-01-01	64.1673265422177
2017-01-01	64.2401594341512