Year	Percent of Total
1960-01-01	64.2966220099894
1961-01-01	64.2436007876805
1962-01-01	64.3828837395505
1963-01-01	64.6605041422485
1964-01-01	64.9403047357141
1965-01-01	65.1240781012250
1966-01-01	65.4936208551721
1967-01-01	65.5629755506968
1968-01-01	65.4782395682552
1969-01-01	65.4585770914111
1970-01-01	65.5940210164909
1971-01-01	65.2341483355168
1972-01-01	65.2872608523326
1973-01-01	65.5039172596692
1974-01-01	65.5338775938325
1975-01-01	65.2363375506556
1976-01-01	65.0191873788305
1977-01-01	64.3907377425616
1978-01-01	63.6117492718803
1979-01-01	63.0886347185692
1980-01-01	63.0119594616498
1981-01-01	63.0343683064820
1982-01-01	63.5092271944217
1983-01-01	64.2497674880091
1984-01-01	64.9245403532352
1985-01-01	65.3493911740164
1986-01-01	65.6856847185594
1987-01-01	65.7451798255076
1988-01-01	65.6577662518217
1989-01-01	65.6516639563412
1990-01-01	65.8457252136956
1991-01-01	65.8068723090389
1992-01-01	66.0593612607996
1993-01-01	66.4867188008941
1994-01-01	66.8843915569942
1995-01-01	67.1456454096826
1996-01-01	67.4880663247262
1997-01-01	67.5952627171047
1998-01-01	67.5831728602587
1999-01-01	67.6427738855837
2000-01-01	67.8562054594044
2001-01-01	67.8734141688995
2002-01-01	68.0646420930697
2003-01-01	68.3681456956050
2004-01-01	68.6572525686897
2005-01-01	68.8654687332165
2006-01-01	68.9294895735354
2007-01-01	68.9022129613216
2008-01-01	68.8029595385139
2009-01-01	68.6755645746632
2010-01-01	68.5340126564388
2011-01-01	68.3876586405526
2012-01-01	68.2428535061403
2013-01-01	68.0817378697772
2014-01-01	67.8671765350526
2015-01-01	67.5835696620668
2016-01-01	67.2701039832829
2017-01-01	66.8858596944425