Year	Percent of Total
1960-01-01	60.7509750585211
1961-01-01	60.5605545737665
1962-01-01	60.6620041231772
1963-01-01	60.9864912308673
1964-01-01	61.3989876133083
1965-01-01	61.8205031831709
1966-01-01	62.4254095564143
1967-01-01	62.9486639389576
1968-01-01	63.4412702722393
1969-01-01	63.9754413353000
1970-01-01	64.5623085274751
1971-01-01	64.9727870893053
1972-01-01	65.4457400249409
1973-01-01	65.9154098949704
1974-01-01	66.2799405731061
1975-01-01	66.4883433041168
1976-01-01	66.4689103623253
1977-01-01	66.3405251278868
1978-01-01	66.1338914916784
1979-01-01	65.9257463414717
1980-01-01	65.7638440271519
1981-01-01	65.6033825977008
1982-01-01	65.4879713118053
1983-01-01	65.3936300133792
1984-01-01	65.2939649981368
1985-01-01	65.1882530710663
1986-01-01	65.0262560379651
1987-01-01	64.9182083421298
1988-01-01	64.8708474397030
1989-01-01	64.8764145246659
1990-01-01	64.9287504453023
1991-01-01	65.0648643849013
1992-01-01	65.1953036906348
1993-01-01	65.3620738576052
1994-01-01	65.6247853896449
1995-01-01	66.0063191513132
1996-01-01	66.3231421409428
1997-01-01	66.7864223859997
1998-01-01	67.3413471540861
1999-01-01	67.9007696083061
2000-01-01	68.4178374363287
2001-01-01	68.8671076644290
2002-01-01	69.2462248150371
2003-01-01	69.5850180231831
2004-01-01	69.9358939533024
2005-01-01	70.3121571373585
2006-01-01	70.6300502678123
2007-01-01	70.9271989247992
2008-01-01	71.1671850178610
2009-01-01	71.3030389926959
2010-01-01	71.3103523533741
2011-01-01	71.0657046131976
2012-01-01	70.7832320790834
2013-01-01	70.4397799905825
2014-01-01	70.0125035711432
2015-01-01	69.5045470265875
2016-01-01	69.0086387206500
2017-01-01	68.4197114269181