Year	Percent of Total
1960-01-01	55.4652496412481
1961-01-01	55.0519468530937
1962-01-01	54.7763314842756
1963-01-01	54.5705730615821
1964-01-01	54.3491744736196
1965-01-01	54.0783437515302
1966-01-01	53.6314260800420
1967-01-01	53.1770349641665
1968-01-01	52.7579230825831
1969-01-01	52.4623323374026
1970-01-01	52.3483172443882
1971-01-01	52.1142859052645
1972-01-01	51.9864574813229
1973-01-01	51.9442764016955
1974-01-01	51.9237921699858
1975-01-01	51.8829172157269
1976-01-01	51.7806197048688
1977-01-01	51.7526944222329
1978-01-01	51.7897237014494
1979-01-01	51.9089671190055
1980-01-01	52.1140957638105
1981-01-01	52.1499423539548
1982-01-01	52.3322575839494
1983-01-01	52.6047167658147
1984-01-01	52.8985302950672
1985-01-01	53.1844804710822
1986-01-01	53.3843474269000
1987-01-01	53.5956198320527
1988-01-01	53.8370499460952
1989-01-01	54.1477015968613
1990-01-01	54.5440914481230
1991-01-01	54.8633448824580
1992-01-01	55.2586361154757
1993-01-01	55.7128242747476
1994-01-01	56.2002082469263
1995-01-01	56.7050705935969
1996-01-01	57.1508005981217
1997-01-01	57.6174586596029
1998-01-01	58.1005301271555
1999-01-01	58.5988538095468
2000-01-01	59.1087652211949
2001-01-01	59.5113810478128
2002-01-01	59.9394188902460
2003-01-01	60.3838960114524
2004-01-01	60.8372971654744
2005-01-01	61.2990365318328
2006-01-01	61.6377947928624
2007-01-01	62.0016410175859
2008-01-01	62.3865637400431
2009-01-01	62.7855679996401
2010-01-01	63.1964275411892
2011-01-01	63.6645794208682
2012-01-01	64.1144791971373
2013-01-01	64.5630785333663
2014-01-01	65.0354264616293
2015-01-01	65.5400287316039
2016-01-01	66.0216686480326
2017-01-01	66.5318015814574