Year	Percent of Total
1960-01-01	63.5484832140567
1961-01-01	63.1751746509523
1962-01-01	63.1199153064950
1963-01-01	63.3138160311490
1964-01-01	63.6003512405549
1965-01-01	63.8967536375684
1966-01-01	64.2910030302942
1967-01-01	64.7138467792911
1968-01-01	65.1588960512837
1969-01-01	65.6171319644001
1970-01-01	66.0672926769046
1971-01-01	66.5900349023583
1972-01-01	67.0130462590174
1973-01-01	67.3589289983772
1974-01-01	67.6636943970030
1975-01-01	67.9397215746795
1976-01-01	67.9310225759916
1977-01-01	68.0012028111501
1978-01-01	68.0988460222240
1979-01-01	68.1576840847422
1980-01-01	68.1518963924840
1981-01-01	68.1503992804033
1982-01-01	68.0616926462907
1983-01-01	67.9091902585897
1984-01-01	67.7533186556010
1985-01-01	67.6245709904251
1986-01-01	67.3854679937985
1987-01-01	67.2067820415130
1988-01-01	67.0680428299466
1989-01-01	66.9326406742697
1990-01-01	66.7916259504533
1991-01-01	66.5196849753294
1992-01-01	66.3346555484406
1993-01-01	66.2520887683226
1994-01-01	66.2955112312288
1995-01-01	66.4820121762502
1996-01-01	66.9766426936859
1997-01-01	67.5113160718270
1998-01-01	68.0891982813986
1999-01-01	68.7004796367148
2000-01-01	69.3134093343234
2001-01-01	69.6069640746639
2002-01-01	69.9062732803488
2003-01-01	70.2267318127966
2004-01-01	70.5894501138804
2005-01-01	71.0077738414533
2006-01-01	71.2683377753650
2007-01-01	71.6041937282885
2008-01-01	71.9044691113848
2009-01-01	72.0583315305984
2010-01-01	72.0224844219893
2011-01-01	71.7919642164366
2012-01-01	71.3715171608162
2013-01-01	70.8289261568625
2014-01-01	70.2513709906147
2015-01-01	69.6787370822101
2016-01-01	68.9174213370207
2017-01-01	68.2161211276186