Year	Percent of Total
1960-01-01	54.8693798158531
1961-01-01	54.6087204006731
1962-01-01	54.3289283792758
1963-01-01	54.0724712675110
1964-01-01	53.9019548652085
1965-01-01	53.8391364659607
1966-01-01	53.6828958341433
1967-01-01	53.6410378438680
1968-01-01	53.6770545786624
1969-01-01	53.7400772880058
1970-01-01	53.8046974464964
1971-01-01	53.7463145503327
1972-01-01	53.7113545082037
1973-01-01	53.6958066808813
1974-01-01	53.7019095060635
1975-01-01	53.7298186755687
1976-01-01	53.6586099868835
1977-01-01	53.6250764888178
1978-01-01	53.6218165946355
1979-01-01	53.6436004680459
1980-01-01	53.6898621958781
1981-01-01	53.6641058076446
1982-01-01	53.6820078055642
1983-01-01	53.7417320626243
1984-01-01	53.8484548493100
1985-01-01	54.0062244381667
1986-01-01	54.1130155868344
1987-01-01	54.2882385930717
1988-01-01	54.5152581406867
1989-01-01	54.7719332118144
1990-01-01	55.0446214624006
1991-01-01	55.2895575340487
1992-01-01	55.5333897766959
1993-01-01	55.7818905311761
1994-01-01	56.0397777556981
1995-01-01	56.3019331153372
1996-01-01	56.4619128124454
1997-01-01	56.6286511306696
1998-01-01	56.7954999812896
1999-01-01	56.9579221280480
2000-01-01	57.1166583097371
2001-01-01	57.1600965124790
2002-01-01	57.2453617307562
2003-01-01	57.3543220417374
2004-01-01	57.4690453665875
2005-01-01	57.5859790213611
2006-01-01	57.6951633563473
2007-01-01	57.7987942525576
2008-01-01	57.9188697762416
2009-01-01	58.0879566263694
2010-01-01	58.3185089865436
2011-01-01	58.5225662604129
2012-01-01	58.7928733725250
2013-01-01	59.1066349790231
2014-01-01	59.4284782262531
2015-01-01	59.7387442273030
2016-01-01	60.0015386535371
2017-01-01	60.2554282657400