Year	Percent of Total
1960-01-01	61.2317726831289
1961-01-01	61.1392135458384
1962-01-01	61.2200654171666
1963-01-01	61.4106589978034
1964-01-01	61.6189652180242
1965-01-01	61.7947864324427
1966-01-01	61.9849046472562
1967-01-01	62.1595705944680
1968-01-01	62.3021508123016
1969-01-01	62.4450482563274
1970-01-01	62.6349159111718
1971-01-01	62.8131105427732
1972-01-01	62.9954924737186
1973-01-01	63.1919340006605
1974-01-01	63.4262666914945
1975-01-01	63.7126654031470
1976-01-01	63.8559323820299
1977-01-01	64.1487443705212
1978-01-01	64.5118369887887
1979-01-01	64.8432120460640
1980-01-01	65.0962167404800
1981-01-01	65.4582264210910
1982-01-01	65.6730424341627
1983-01-01	65.8035617962166
1984-01-01	65.9482848238553
1985-01-01	66.1435164167426
1986-01-01	66.2195571120126
1987-01-01	66.3996933854242
1988-01-01	66.6191355824832
1989-01-01	66.7811795100777
1990-01-01	66.8484765158513
1991-01-01	66.8549342126975
1992-01-01	66.7735887124907
1993-01-01	66.6530713619504
1994-01-01	66.5711742000120
1995-01-01	66.5608677403889
1996-01-01	66.5439230153103
1997-01-01	66.5871363385408
1998-01-01	66.6667613177466
1999-01-01	66.7406236773827
2000-01-01	66.7885758175736
2001-01-01	66.9227750758192
2002-01-01	67.0428290022932
2003-01-01	67.1476610719658
2004-01-01	67.2395054267181
2005-01-01	67.3083763482636
2006-01-01	67.4658686474311
2007-01-01	67.5877170703650
2008-01-01	67.6431005506245
2009-01-01	67.6227469106272
2010-01-01	67.5364546865687
2011-01-01	67.2771807256817
2012-01-01	67.0264972833708
2013-01-01	66.7686274587725
2014-01-01	66.4895239412971
2015-01-01	66.1877053504696
2016-01-01	65.8488024959786
2017-01-01	65.4838798995246