Year	Percent of Total
1960-01-01	54.4437901019141
1961-01-01	54.1360351601367
1962-01-01	53.9553752535497
1963-01-01	53.8737513379282
1964-01-01	53.8584851152534
1965-01-01	53.8891624628435
1966-01-01	53.6613233005793
1967-01-01	53.5150588741813
1968-01-01	53.4331426350404
1969-01-01	53.4289733949851
1970-01-01	53.5265388571463
1971-01-01	53.3509263112032
1972-01-01	53.3526694219490
1973-01-01	53.4633976876265
1974-01-01	53.4984937301241
1975-01-01	53.2375164934851
1976-01-01	53.1043586047597
1977-01-01	52.9977035076300
1978-01-01	52.8675979282874
1979-01-01	52.8299025046127
1980-01-01	53.0451354478587
1981-01-01	52.9412379225517
1982-01-01	52.8823270871746
1983-01-01	52.9428119556928
1984-01-01	53.1007425682416
1985-01-01	53.2784792532550
1986-01-01	53.1625270132062
1987-01-01	53.0708628207399
1988-01-01	52.9815590286234
1989-01-01	52.9125562433607
1990-01-01	52.9021553267678
1991-01-01	52.6250493566468
1992-01-01	52.4342649251977
1993-01-01	52.3016735394015
1994-01-01	52.1543907043740
1995-01-01	51.9178719395750
1996-01-01	51.5253492953781
1997-01-01	51.1413184065082
1998-01-01	50.7627423723388
1999-01-01	50.4375514822945
2000-01-01	50.2071524552185
2001-01-01	49.8411604655476
2002-01-01	49.6372658486620
2003-01-01	49.5482238059322
2004-01-01	49.5058731376952
2005-01-01	49.4754381035406
2006-01-01	49.4504034541990
2007-01-01	49.4256787729164
2008-01-01	49.4318547636631
2009-01-01	49.5200457123725
2010-01-01	49.7053277783046
2011-01-01	49.7712121792301
2012-01-01	49.9532426767753
2013-01-01	50.1995492200215
2014-01-01	50.4412635863281
2015-01-01	50.6462803156341
2016-01-01	50.7487360661366
2017-01-01	50.8364409538313