Year	Percent of Total
1960-01-01	57.3114067820406
1961-01-01	57.5360792330336
1962-01-01	57.6795007042710
1963-01-01	57.8297198617080
1964-01-01	58.1026816583086
1965-01-01	58.5346815437017
1966-01-01	58.9494706989889
1967-01-01	59.4865597166589
1968-01-01	60.1002511960363
1969-01-01	60.7116126262629
1970-01-01	61.2776615527662
1971-01-01	61.6609974814906
1972-01-01	62.0646329594588
1973-01-01	62.4263422333171
1974-01-01	62.6909467506689
1975-01-01	62.8470723956051
1976-01-01	63.1226609814456
1977-01-01	63.2552865398319
1978-01-01	63.3405017233960
1979-01-01	63.5141079686491
1980-01-01	63.8395652835962
1981-01-01	64.2542736913671
1982-01-01	64.7839680285264
1983-01-01	65.3641725524507
1984-01-01	65.8882757677590
1985-01-01	66.2980297082967
1986-01-01	66.4623267580293
1987-01-01	66.5660948243063
1988-01-01	66.6138481683657
1989-01-01	66.6221636861688
1990-01-01	66.6046163063538
1991-01-01	66.5249420308613
1992-01-01	66.4132463132191
1993-01-01	66.2986107050909
1994-01-01	66.2199633345663
1995-01-01	66.1937060948382
1996-01-01	66.3270071070144
1997-01-01	66.5536440056231
1998-01-01	66.8420924456911
1999-01-01	67.1423151817284
2000-01-01	67.4292406351621
2001-01-01	67.7211453455529
2002-01-01	67.9654433928376
2003-01-01	68.1952989783903
2004-01-01	68.4630929677348
2005-01-01	68.7898491073023
2006-01-01	69.0854496412031
2007-01-01	69.4618820619930
2008-01-01	69.8685968410228
2009-01-01	70.2284527568360
2010-01-01	70.4977305203601
2011-01-01	70.7210491496987
2012-01-01	70.8291466493349
2013-01-01	70.8311594087696
2014-01-01	70.7598333569997
2015-01-01	70.6346053590906
2016-01-01	70.3479136615981
2017-01-01	70.0497801417078