Year	Percent of Total
1960-01-01	49.2227178645567
1961-01-01	48.9117954706853
1962-01-01	48.6615086908787
1963-01-01	48.4819278035567
1964-01-01	48.3953777000050
1965-01-01	48.4142349936117
1966-01-01	48.4846084158571
1967-01-01	48.6535507304171
1968-01-01	48.9030299821766
1969-01-01	49.2128067889473
1970-01-01	49.5727623151446
1971-01-01	49.9491698973508
1972-01-01	50.3685345216971
1973-01-01	50.8198900650300
1974-01-01	51.2961221227806
1975-01-01	51.7922847569921
1976-01-01	52.2746033071608
1977-01-01	52.7748382489216
1978-01-01	53.2769720017094
1979-01-01	53.7609777144930
1980-01-01	54.2166665031349
1981-01-01	54.6436152824109
1982-01-01	55.0235407529751
1983-01-01	55.3678708938919
1984-01-01	55.6966684782917
1985-01-01	56.0217086031806
1986-01-01	56.3045552265420
1987-01-01	56.5991103127092
1988-01-01	56.8896599836948
1989-01-01	57.1525629151588
1990-01-01	57.3801440967241
1991-01-01	57.6261920148214
1992-01-01	57.8244829552613
1993-01-01	57.9997149037669
1994-01-01	58.1897683647678
1995-01-01	58.4148492801260
1996-01-01	58.6520827394010
1997-01-01	58.9397623952162
1998-01-01	59.2543490379835
1999-01-01	59.5544702692288
2000-01-01	59.8189666669859
2001-01-01	60.1283573447136
2002-01-01	60.3729499217926
2003-01-01	60.5861329919623
2004-01-01	60.8165573583560
2005-01-01	61.0845324406884
2006-01-01	61.3425852316926
2007-01-01	61.6468369809076
2008-01-01	61.9668822354958
2009-01-01	62.2561390239193
2010-01-01	62.4936489598641
2011-01-01	62.7382008448110
2012-01-01	62.9303246200129
2013-01-01	63.0864435767631
2014-01-01	63.2344959236367
2015-01-01	63.3884807122530
2016-01-01	63.5542663951241
2017-01-01	63.7208625839812