Year	Percent of Total
1960-01-01	51.0949471540519
1961-01-01	50.8669994274487
1962-01-01	50.6322175267736
1963-01-01	50.4621530175113
1964-01-01	50.4430264093340
1965-01-01	50.6073911441094
1966-01-01	50.7363037031120
1967-01-01	51.1029375168970
1968-01-01	51.5987830799993
1969-01-01	52.0694693620176
1970-01-01	52.4407861622821
1971-01-01	52.9961839893158
1972-01-01	53.3748677947884
1973-01-01	53.6695944291829
1974-01-01	54.0147177635213
1975-01-01	54.4619966718655
1976-01-01	54.8832602862178
1977-01-01	55.4079708559744
1978-01-01	55.9791920624665
1979-01-01	56.4998397869393
1980-01-01	56.9198568646102
1981-01-01	57.2338939736123
1982-01-01	57.4682669375970
1983-01-01	57.6458045983644
1984-01-01	57.8094048530029
1985-01-01	57.9797976042221
1986-01-01	58.1653578203915
1987-01-01	58.4003868537500
1988-01-01	58.6818344441973
1989-01-01	58.9820660629514
1990-01-01	59.2771744110774
1991-01-01	59.5451058622666
1992-01-01	59.7975334833662
1993-01-01	60.0479395528087
1994-01-01	60.3175110650009
1995-01-01	60.6170144738892
1996-01-01	60.9827676607326
1997-01-01	61.3704639276245
1998-01-01	61.7868688505790
1999-01-01	62.2374823481660
2000-01-01	62.7199424746593
2001-01-01	63.0421352343380
2002-01-01	63.4871151314005
2003-01-01	64.0266481394345
2004-01-01	64.5976348159929
2005-01-01	65.1395455847299
2006-01-01	65.4637358958606
2007-01-01	65.8060166728981
2008-01-01	66.1965413462671
2009-01-01	66.6485011274794
2010-01-01	67.1325447742800
2011-01-01	67.6603226638274
2012-01-01	68.1293052120954
2013-01-01	68.5319592964879
2014-01-01	68.8766616744988
2015-01-01	69.1735728313059
2016-01-01	69.3022167862427
2017-01-01	69.3937446259619