Year	Percent of Total
1960-01-01	10.6026258753081
1961-01-01	10.7630926303639
1962-01-01	10.9266765691347
1963-01-01	11.0899927213040
1964-01-01	11.2474540231674
1965-01-01	11.3993815723691
1966-01-01	11.5862088232492
1967-01-01	11.7656286994862
1968-01-01	11.9407702481757
1969-01-01	12.1163245865575
1970-01-01	12.2960325808453
1971-01-01	12.5373002574489
1972-01-01	12.7677612830340
1973-01-01	12.9897306252352
1974-01-01	13.2052701828592
1975-01-01	13.4159067175035
1976-01-01	13.6492335474597
1977-01-01	13.8700168430924
1978-01-01	14.0763138272576
1979-01-01	14.2620392220145
1980-01-01	14.4252719340274
1981-01-01	14.6049263867194
1982-01-01	14.7509373263465
1983-01-01	14.8748722314037
1984-01-01	14.9908581959000
1985-01-01	15.1055982283204
1986-01-01	15.2614339534401
1987-01-01	15.3946913563600
1988-01-01	15.5003639866228
1989-01-01	15.5706001975300
1990-01-01	15.6012849352718
1991-01-01	15.5875914759293
1992-01-01	15.5393153055601
1993-01-01	15.4607568628917
1994-01-01	15.3573537984708
1995-01-01	15.2363481672191
1996-01-01	15.1756278949392
1997-01-01	15.1023047681087
1998-01-01	15.0205485305862
1999-01-01	14.9352264865062
2000-01-01	14.8537574182851
2001-01-01	14.8822092764138
2002-01-01	14.9049257547413
2003-01-01	14.9428769578731
2004-01-01	15.0210790371812
2005-01-01	15.1526955926386
2006-01-01	15.3890406173205
2007-01-01	15.6579658670077
2008-01-01	15.9604168580313
2009-01-01	16.2972701990990
2010-01-01	16.6677047996307
2011-01-01	17.0323057680159
2012-01-01	17.4895823307775
2013-01-01	18.0262857059745
2014-01-01	18.5702325282481
2015-01-01	19.0474440974600
2016-01-01	19.4308518926376
2017-01-01	19.6772645782692