Year	Percent of Total
1960-01-01	2.60903882132834
1961-01-01	2.66916335344229
1962-01-01	2.71871603630958
1963-01-01	2.76037687130309
1964-01-01	2.79846008206651
1965-01-01	2.83480945557657
1966-01-01	2.89308444257862
1967-01-01	2.94659019912532
1968-01-01	2.99293819118197
1969-01-01	3.02892574283497
1970-01-01	3.05394081597127
1971-01-01	3.09593757297001
1972-01-01	3.12590532169875
1973-01-01	3.14665875605927
1974-01-01	3.16275850770571
1975-01-01	3.17655428652136
1976-01-01	3.25049621277759
1977-01-01	3.31981011798426
1978-01-01	3.38388490688873
1979-01-01	3.44024683474843
1980-01-01	3.48812084425980
1981-01-01	3.52259162893647
1982-01-01	3.54605758719903
1983-01-01	3.55939308482549
1984-01-01	3.56336931296480
1985-01-01	3.55915483562723
1986-01-01	3.57022838170258
1987-01-01	3.57014547152065
1988-01-01	3.56123120318285
1989-01-01	3.54633955859355
1990-01-01	3.52725108912305
1991-01-01	3.53866248347916
1992-01-01	3.54409451214840
1993-01-01	3.54313387897770
1994-01-01	3.53591906134107
1995-01-01	3.52400481211264
1996-01-01	3.54110603205855
1997-01-01	3.55513348214454
1998-01-01	3.56576297531065
1999-01-01	3.57200640148483
2000-01-01	3.57393760986425
2001-01-01	3.60721298541269
2002-01-01	3.63185528533875
2003-01-01	3.64891670740992
2004-01-01	3.65894885874655
2005-01-01	3.66195773185592
2006-01-01	3.67691759571481
2007-01-01	3.68344278543081
2008-01-01	3.68526103774006
2009-01-01	3.68637309664638
2010-01-01	3.69002384461521
2011-01-01	3.72008342323905
2012-01-01	3.75327602437286
2013-01-01	3.79075893860043
2014-01-01	3.83437922011095
2015-01-01	3.88537338195102
2016-01-01	3.95584545524627
2017-01-01	4.02927315781492