Year	Percent of Total
1960-01-01	52.4946240445256
1961-01-01	52.6325163864349
1962-01-01	52.6914461710766
1963-01-01	52.7138298967304
1964-01-01	52.7904710704926
1965-01-01	52.9622743949590
1966-01-01	53.2606068418763
1967-01-01	53.5716540404040
1968-01-01	53.9231304616812
1969-01-01	54.3134577454104
1970-01-01	54.7527497093803
1971-01-01	55.0346101953423
1972-01-01	55.4079449520065
1973-01-01	55.8444894813462
1974-01-01	56.2896808600694
1975-01-01	56.7470569341842
1976-01-01	57.3272463166632
1977-01-01	57.9581475128645
1978-01-01	58.6206426272435
1979-01-01	59.3120987922968
1980-01-01	60.0147054818768
1981-01-01	60.8039306927983
1982-01-01	61.3819567137809
1983-01-01	61.8350339898658
1984-01-01	62.2764227642276
1985-01-01	62.7253446447508
1986-01-01	62.8566030606461
1987-01-01	62.9744270027268
1988-01-01	62.8530525813475
1989-01-01	62.2810572290513
1990-01-01	61.2660429411059
1991-01-01	61.5225756607782
1992-01-01	61.5678021833487
1993-01-01	61.5673882581715
1994-01-01	61.6837936948368
1995-01-01	61.9378149662451
1996-01-01	62.6037975353044
1997-01-01	63.1214705617515
1998-01-01	63.4719665376764
1999-01-01	63.6971318937811
2000-01-01	63.9045750382849
2001-01-01	64.1428688996790
2002-01-01	64.4471750168085
2003-01-01	64.7039281500235
2004-01-01	64.8288521023828
2005-01-01	64.8314342375046
2006-01-01	65.1587468577314
2007-01-01	65.4917324170232
2008-01-01	65.8535002919613
2009-01-01	66.2645195071649
2010-01-01	66.7349806150368
2011-01-01	67.1674380217094
2012-01-01	67.6400384388853
2013-01-01	68.1121197252208
2014-01-01	68.5259165613148
2015-01-01	68.8580206759205
2016-01-01	69.0520289611046
2017-01-01	69.1732345214289