Year	Percent of Total
1960-01-01	55.6582876278445
1961-01-01	55.4558950021753
1962-01-01	55.4874682116399
1963-01-01	55.6322940952376
1964-01-01	55.7298193148991
1965-01-01	55.7098244351855
1966-01-01	55.3446698164562
1967-01-01	54.9423675098304
1968-01-01	54.5430569398460
1969-01-01	54.2281941329204
1970-01-01	54.0348476262772
1971-01-01	53.6214210621307
1972-01-01	53.3729418980841
1973-01-01	53.2509450302915
1974-01-01	53.2021682443071
1975-01-01	53.1954358822733
1976-01-01	52.9815986586907
1977-01-01	52.8588941591358
1978-01-01	52.8147975201908
1979-01-01	52.8401507148714
1980-01-01	52.9197547236859
1981-01-01	52.8071806601129
1982-01-01	52.8046824586979
1983-01-01	52.8787028401964
1984-01-01	53.0004742829783
1985-01-01	53.1688360391779
1986-01-01	53.0611467520252
1987-01-01	52.9413467304898
1988-01-01	52.8488731083121
1989-01-01	52.8514765388063
1990-01-01	53.0013880603923
1991-01-01	52.7883340946034
1992-01-01	52.7319300248187
1993-01-01	52.7849547844029
1994-01-01	52.8100029861529
1995-01-01	52.6535029917471
1996-01-01	52.5052967977401
1997-01-01	52.3810260945723
1998-01-01	52.2465119641674
1999-01-01	52.1499832028903
2000-01-01	52.1453123395679
2001-01-01	52.0524222582968
2002-01-01	52.0844306614809
2003-01-01	52.2117824337658
2004-01-01	52.3750602716736
2005-01-01	52.5282847427579
2006-01-01	52.6151868790263
2007-01-01	52.7233989702827
2008-01-01	52.8575635724230
2009-01-01	53.0421738231706
2010-01-01	53.2942155071643
2011-01-01	53.4280352386869
2012-01-01	53.6223576845736
2013-01-01	53.8678361599966
2014-01-01	54.1459171131382
2015-01-01	54.4457915647489
2016-01-01	54.6579312927356
2017-01-01	54.8852256022998