Year	Percent of Total
1960-01-01	55.1084918528269
1961-01-01	54.6612108184636
1962-01-01	54.3463493073530
1963-01-01	54.1233030947784
1964-01-01	53.9329004421289
1965-01-01	53.7578492101931
1966-01-01	53.7683652200437
1967-01-01	53.8713808157349
1968-01-01	54.0562987196405
1969-01-01	54.3064061232467
1970-01-01	54.6221864951768
1971-01-01	55.6148061740996
1972-01-01	56.4262076449319
1973-01-01	57.1167522718293
1974-01-01	57.8140910038890
1975-01-01	58.5715795377875
1976-01-01	58.8670567886067
1977-01-01	59.3237507235192
1978-01-01	59.7063575862290
1979-01-01	59.8223563463215
1980-01-01	59.6988826062476
1981-01-01	60.4899636478584
1982-01-01	61.0677550119957
1983-01-01	61.5638186690136
1984-01-01	62.1384599107342
1985-01-01	62.8424844875823
1986-01-01	63.3518478125390
1987-01-01	64.0186172174325
1988-01-01	64.7444947723062
1989-01-01	65.3743573140932
1990-01-01	65.8364506440735
1991-01-01	66.1682135680796
1992-01-01	66.3198364507369
1993-01-01	66.3634739574821
1994-01-01	66.3981213188645
1995-01-01	66.4695292479214
1996-01-01	66.4972061577336
1997-01-01	66.5504130064245
1998-01-01	66.5986191453630
1999-01-01	66.5970058232499
2000-01-01	66.5314048331091
2001-01-01	66.8319264089255
2002-01-01	67.0518421382211
2003-01-01	67.2189614262942
2004-01-01	67.3815687811023
2005-01-01	67.5525256469678
2006-01-01	67.6351353808005
2007-01-01	67.7237008871990
2008-01-01	67.7807867473920
2009-01-01	67.7505655905483
2010-01-01	67.6140773834009
2011-01-01	67.5564235337721
2012-01-01	67.3824955164515
2013-01-01	67.1143220215993
2014-01-01	66.8013479894843
2015-01-01	66.4703378052685
2016-01-01	66.2412805793766
2017-01-01	65.9872112110150