Year	Percent of Total
1960-01-01	62.7288980366588
1961-01-01	62.6742804584464
1962-01-01	62.6105237344951
1963-01-01	62.5237889592406
1964-01-01	62.4106552818472
1965-01-01	62.2946830937766
1966-01-01	62.0124170364898
1967-01-01	61.8423477164944
1968-01-01	61.7623136531534
1969-01-01	61.7046759531555
1970-01-01	61.6091741358595
1971-01-01	61.7770675204382
1972-01-01	61.8743011716560
1973-01-01	61.9191040212024
1974-01-01	61.9757573091053
1975-01-01	62.0835903152831
1976-01-01	62.0808779181429
1977-01-01	62.1723287572721
1978-01-01	62.3331636058284
1979-01-01	62.5234091264711
1980-01-01	62.7308359912863
1981-01-01	63.0124967886912
1982-01-01	63.2969628729537
1983-01-01	63.5811093269141
1984-01-01	63.8742877738453
1985-01-01	64.1864289237225
1986-01-01	64.4547085554853
1987-01-01	64.7584406060915
1988-01-01	65.1027371394779
1989-01-01	65.4666688914411
1990-01-01	65.8191276143143
1991-01-01	66.1568276938640
1992-01-01	66.4691191714814
1993-01-01	66.7466700135932
1994-01-01	66.9921728662200
1995-01-01	67.2088975722026
1996-01-01	67.3247423519931
1997-01-01	67.4479354989268
1998-01-01	67.5611835573893
1999-01-01	67.6373616730041
2000-01-01	67.6591196410432
2001-01-01	67.6421863292495
2002-01-01	67.5786897860024
2003-01-01	67.4793434570601
2004-01-01	67.3818238669456
2005-01-01	67.3164250094385
2006-01-01	67.0401495252195
2007-01-01	66.8250217307048
2008-01-01	66.6610496203612
2009-01-01	66.5132671507913
2010-01-01	66.3506291258027
2011-01-01	66.1473102482464
2012-01-01	65.9274807237809
2013-01-01	65.6866084569108
2014-01-01	65.4351453438623
2015-01-01	65.1844948871106
2016-01-01	65.0184585311446
2017-01-01	64.8630341083107