Year	Percent of Total
1960-01-01	50.7064499627392
1961-01-01	50.4514733998668
1962-01-01	50.1412708045159
1963-01-01	49.8349041532785
1964-01-01	49.6211007549139
1965-01-01	49.5351179882555
1966-01-01	49.4519771538299
1967-01-01	49.4768353709688
1968-01-01	49.5740838976644
1969-01-01	49.6773854228747
1970-01-01	49.7484742463563
1971-01-01	49.7570995915688
1972-01-01	49.7209847530787
1973-01-01	49.6767726908944
1974-01-01	49.6896850441847
1975-01-01	49.7960430309310
1976-01-01	49.8055027450203
1977-01-01	49.9876542219857
1978-01-01	50.2774521813373
1979-01-01	50.5918923951932
1980-01-01	50.9016892247504
1981-01-01	51.3924425072362
1982-01-01	51.8076139299438
1983-01-01	52.2113023371384
1984-01-01	52.6903354756801
1985-01-01	53.2737388245431
1986-01-01	53.9132472805647
1987-01-01	54.6169019778281
1988-01-01	55.3504651745490
1989-01-01	56.0501709654787
1990-01-01	56.6807498040544
1991-01-01	57.2390416282193
1992-01-01	57.7719490554306
1993-01-01	58.2684823882724
1994-01-01	58.7260334954691
1995-01-01	59.1475480203062
1996-01-01	59.5150898155382
1997-01-01	59.8313985731690
1998-01-01	60.1163860609380
1999-01-01	60.4005615959605
2000-01-01	60.7016373322396
2001-01-01	61.0186194488428
2002-01-01	61.3512692101799
2003-01-01	61.6901519723699
2004-01-01	62.0175040309841
2005-01-01	62.3252958351699
2006-01-01	62.7313572970510
2007-01-01	63.1252786102293
2008-01-01	63.5142301843885
2009-01-01	63.9063714068423
2010-01-01	64.3006034294155
2011-01-01	64.6882609816069
2012-01-01	65.0640739342644
2013-01-01	65.4210503693001
2014-01-01	65.7502930247236
2015-01-01	66.0458322543903
2016-01-01	66.2635414028696
2017-01-01	66.4750861537455