Year	Percent of Total
1960-01-01	57.3890353097237
1961-01-01	57.3074020420025
1962-01-01	57.4989051240196
1963-01-01	57.9552631624483
1964-01-01	58.5548202901005
1965-01-01	59.1776455076545
1966-01-01	59.1611595946066
1967-01-01	59.1262083381250
1968-01-01	59.0783852108546
1969-01-01	59.0279370348433
1970-01-01	58.9648985285706
1971-01-01	59.8491767051778
1972-01-01	60.7146155585492
1973-01-01	61.4550842293709
1974-01-01	62.0525921670644
1975-01-01	62.5646589868489
1976-01-01	63.1780257750930
1977-01-01	63.8115901960549
1978-01-01	64.4382258622713
1979-01-01	65.0533594309504
1980-01-01	65.6586023466383
1981-01-01	65.5356492491726
1982-01-01	65.4609933179317
1983-01-01	65.3902953130560
1984-01-01	65.3100039127612
1985-01-01	65.2248798116208
1986-01-01	65.0813304302293
1987-01-01	65.0192153501617
1988-01-01	64.9313829722232
1989-01-01	64.7798264815377
1990-01-01	64.6030466440738
1991-01-01	64.7201163537553
1992-01-01	64.8622486132432
1993-01-01	65.0189129539994
1994-01-01	65.2223722091481
1995-01-01	65.4911712166699
1996-01-01	65.6694408093215
1997-01-01	66.0168628084633
1998-01-01	66.4539828150861
1999-01-01	66.9133416122240
2000-01-01	67.3709776250257
2001-01-01	67.7347904053184
2002-01-01	68.1120939725640
2003-01-01	68.4848368950937
2004-01-01	68.8590770083431
2005-01-01	69.2369445866232
2006-01-01	69.5418212564407
2007-01-01	69.8722962606420
2008-01-01	70.1950787887530
2009-01-01	70.4903850006739
2010-01-01	70.7463641699180
2011-01-01	70.7173941066912
2012-01-01	70.6636289471412
2013-01-01	70.5638449649269
2014-01-01	70.4260749503822
2015-01-01	70.2717950705651
2016-01-01	70.0046576220489
2017-01-01	69.7534909469790