Year	Percent of Total
1960-01-01	65.6692694535885
1961-01-01	65.4368935999082
1962-01-01	65.3418191320440
1963-01-01	65.3430181208859
1964-01-01	65.3910732312831
1965-01-01	65.4619177228782
1966-01-01	65.3332339571219
1967-01-01	65.2266418144230
1968-01-01	65.1342117816293
1969-01-01	65.0644297484006
1970-01-01	65.0302673308957
1971-01-01	64.8842466650647
1972-01-01	64.8002486714371
1973-01-01	64.7785352337440
1974-01-01	64.8275162740878
1975-01-01	64.9578953413093
1976-01-01	65.0722947871281
1977-01-01	65.2360341078421
1978-01-01	65.4751575368957
1979-01-01	65.7984989865281
1980-01-01	66.1822987145461
1981-01-01	66.6075405790578
1982-01-01	67.0723142046705
1983-01-01	67.5273145530998
1984-01-01	67.9187682774882
1985-01-01	68.2195661117086
1986-01-01	68.3253809697007
1987-01-01	68.4050050452480
1988-01-01	68.4496184421020
1989-01-01	68.4476643922072
1990-01-01	68.3921382974101
1991-01-01	68.2835615538129
1992-01-01	68.1201301292841
1993-01-01	67.9321783040223
1994-01-01	67.7710783229997
1995-01-01	67.6699306478213
1996-01-01	67.4721607868834
1997-01-01	67.3406549709417
1998-01-01	67.2728399647680
1999-01-01	67.2483043971364
2000-01-01	67.2531305591405
2001-01-01	67.3498702220075
2002-01-01	67.4757182374059
2003-01-01	67.6199307916339
2004-01-01	67.7669064344781
2005-01-01	67.8981224532098
2006-01-01	68.0040933476818
2007-01-01	68.0830458028575
2008-01-01	68.1227572754941
2009-01-01	68.1124122917954
2010-01-01	68.0443658435405
2011-01-01	67.9412101829146
2012-01-01	67.8050019485362
2013-01-01	67.6274248789513
2014-01-01	67.4237319811136
2015-01-01	67.2186451330560
2016-01-01	66.9424032334258
2017-01-01	66.6893660397794