Year	Percent of Total
1960-01-01	50.5467117867355
1961-01-01	50.4444037975583
1962-01-01	50.3742169060378
1963-01-01	50.3431885284613
1964-01-01	50.3888476794881
1965-01-01	50.5407406495861
1966-01-01	50.6645806909645
1967-01-01	50.8942140462057
1968-01-01	51.2286434064477
1969-01-01	51.6387196531685
1970-01-01	52.1013917686978
1971-01-01	52.3273426619802
1972-01-01	52.5699443734984
1973-01-01	52.8393746522453
1974-01-01	53.1409522258108
1975-01-01	53.4707156584905
1976-01-01	53.6969904923017
1977-01-01	53.9409246407976
1978-01-01	54.1923553060574
1979-01-01	54.4348604900794
1980-01-01	54.6536490695197
1981-01-01	54.7581970448299
1982-01-01	54.8613122103733
1983-01-01	54.9400893860876
1984-01-01	55.0003793736240
1985-01-01	55.0759087749198
1986-01-01	55.1929739956467
1987-01-01	55.3266259704519
1988-01-01	55.4845679835677
1989-01-01	55.6595362061128
1990-01-01	55.8364273569520
1991-01-01	56.0199693455170
1992-01-01	56.1963436764199
1993-01-01	56.3998703441773
1994-01-01	56.6609844831791
1995-01-01	56.9784043905962
1996-01-01	57.1310797355346
1997-01-01	57.3526862244969
1998-01-01	57.6055529432349
1999-01-01	57.8446182970070
2000-01-01	58.0606109131671
2001-01-01	58.5646490136765
2002-01-01	58.9947994805224
2003-01-01	59.3804878578038
2004-01-01	59.7481921203887
2005-01-01	60.0983154789825
2006-01-01	60.2324600711596
2007-01-01	60.3556408719515
2008-01-01	60.4763100660039
2009-01-01	60.6137617130600
2010-01-01	60.7794798280712
2011-01-01	60.7539913920231
2012-01-01	60.8207736510122
2013-01-01	60.9281931444392
2014-01-01	61.0184955020928
2015-01-01	61.0748643307062
2016-01-01	61.2163778949943
2017-01-01	61.3048293785145