Year	Percent of Total
1960-01-01	64.6156774602080
1961-01-01	64.2000510112996
1962-01-01	63.9481383179261
1963-01-01	63.8088029279213
1964-01-01	63.6919205832648
1965-01-01	63.5567214061844
1966-01-01	63.3492830933633
1967-01-01	63.1859215228561
1968-01-01	63.0656430676816
1969-01-01	63.0025508218997
1970-01-01	63.0051037252211
1971-01-01	63.0385879641415
1972-01-01	63.1143216347397
1973-01-01	63.2463343147723
1974-01-01	63.4503058370661
1975-01-01	63.7273621702761
1976-01-01	63.9243649957523
1977-01-01	64.1884601499323
1978-01-01	64.5232185949638
1979-01-01	64.9328009269383
1980-01-01	65.4132158340338
1981-01-01	65.8708202909300
1982-01-01	66.3814037540001
1983-01-01	66.8836053781214
1984-01-01	67.2992461114166
1985-01-01	67.5822143485384
1986-01-01	67.6069356407013
1987-01-01	67.5367714617831
1988-01-01	67.3995433285604
1989-01-01	67.2390847616315
1990-01-01	67.0824212635252
1991-01-01	66.9023437052546
1992-01-01	66.7152670924810
1993-01-01	66.5234002004610
1994-01-01	66.3409387176089
1995-01-01	66.1818097926579
1996-01-01	65.9813141789382
1997-01-01	65.8344181398892
1998-01-01	65.7301696472869
1999-01-01	65.6458602303621
2000-01-01	65.5677043635242
2001-01-01	65.5524134610083
2002-01-01	65.5291882157882
2003-01-01	65.5082929009144
2004-01-01	65.5152323204025
2005-01-01	65.5588768097048
2006-01-01	65.5870149884642
2007-01-01	65.6686703431115
2008-01-01	65.7632083648718
2009-01-01	65.8123125625559
2010-01-01	65.7832315041066
2011-01-01	65.6495006893165
2012-01-01	65.4772342796306
2013-01-01	65.2732024141659
2014-01-01	65.0596243337626
2015-01-01	64.8535339486213
2016-01-01	64.6001511307203
2017-01-01	64.3341572948770