Year	Percent of Total
1960-01-01	58.5668766903475
1961-01-01	58.4778273564268
1962-01-01	58.4806392411367
1963-01-01	58.5948394972574
1964-01-01	58.8103173473949
1965-01-01	59.1137955221685
1966-01-01	59.1580852688063
1967-01-01	59.4138634706327
1968-01-01	59.8033656812822
1969-01-01	60.2045048966150
1970-01-01	60.5507951412129
1971-01-01	60.9507829242750
1972-01-01	61.2226838158254
1973-01-01	61.4629527706039
1974-01-01	61.8055853258428
1975-01-01	62.3032579082649
1976-01-01	62.7904249782312
1977-01-01	63.4156257975566
1978-01-01	64.1267452778421
1979-01-01	64.8290490596472
1980-01-01	65.4697591184383
1981-01-01	66.1591408524454
1982-01-01	66.7628613160591
1983-01-01	67.2980887656896
1984-01-01	67.8050384922494
1985-01-01	68.2965895818202
1986-01-01	68.6102639068750
1987-01-01	68.8746659330908
1988-01-01	69.0731215406375
1989-01-01	69.1923917816615
1990-01-01	69.2550245081016
1991-01-01	69.2921109259006
1992-01-01	69.2547380916098
1993-01-01	69.1631529264073
1994-01-01	69.0149908225656
1995-01-01	68.7814539694962
1996-01-01	68.7100073061477
1997-01-01	68.6051788827030
1998-01-01	68.4805298514726
1999-01-01	68.3783802477070
2000-01-01	68.3337112054936
2001-01-01	68.2410022687233
2002-01-01	68.2594475829935
2003-01-01	68.3791506614942
2004-01-01	68.5685588002180
2005-01-01	68.8060917142003
2006-01-01	69.1722750397675
2007-01-01	69.4941176470588
2008-01-01	69.7792724464004
2009-01-01	70.0563263216587
2010-01-01	70.3263010721950
2011-01-01	70.2337982008016
2012-01-01	70.2121045995285
2013-01-01	70.1997975588898
2014-01-01	70.0840605249240
2015-01-01	69.8052099556528
2016-01-01	69.6459524751935
2017-01-01	69.3015460147470