Year	Percent of Total
1960-01-01	53.9069331421684
1961-01-01	53.8230849522504
1962-01-01	53.9319257876961
1963-01-01	54.1294702517774
1964-01-01	54.3091851695107
1965-01-01	54.4548021332856
1966-01-01	54.6664209362330
1967-01-01	54.7049974928966
1968-01-01	54.6821305841924
1969-01-01	54.7732452705039
1970-01-01	55.0726151189830
1971-01-01	55.3314953213198
1972-01-01	55.8633249972817
1973-01-01	56.5786109354183
1974-01-01	57.3084451808155
1975-01-01	57.9729531871847
1976-01-01	59.1067625133120
1977-01-01	60.1583007714658
1978-01-01	61.1512868548100
1979-01-01	62.0912211603957
1980-01-01	62.9429173761453
1981-01-01	63.7183725794481
1982-01-01	64.3198892577311
1983-01-01	64.8388822035031
1984-01-01	65.3172378434885
1985-01-01	65.7547364291082
1986-01-01	65.8463117348741
1987-01-01	65.8038895288099
1988-01-01	65.6719737924154
1989-01-01	65.4758835899871
1990-01-01	65.2426178317459
1991-01-01	65.1160087254426
1992-01-01	64.9694222063950
1993-01-01	64.8315084657391
1994-01-01	64.7097329888028
1995-01-01	64.6041255455784
1996-01-01	64.6352028059697
1997-01-01	64.6547585781943
1998-01-01	64.7157227283021
1999-01-01	64.7869496913879
2000-01-01	64.8263802148388
2001-01-01	65.4589835504349
2002-01-01	65.8888914762980
2003-01-01	66.2219479616625
2004-01-01	66.5269942336353
2005-01-01	66.7867134488462
2006-01-01	66.8584815539280
2007-01-01	66.9766343414663
2008-01-01	67.0893866743004
2009-01-01	67.0909381448313
2010-01-01	66.9584304373747
2011-01-01	66.9685841971406
2012-01-01	66.7621008595614
2013-01-01	66.4172503954292
2014-01-01	66.0326364751584
2015-01-01	65.6357192582748
2016-01-01	65.2697165732787
2017-01-01	64.9424750372184