Year	Percent of Total
1960-01-01	3.64994363021421
1961-01-01	3.64340315695423
1962-01-01	3.62541757792785
1963-01-01	3.60281706536290
1964-01-01	3.57421059167523
1965-01-01	3.53947368421053
1966-01-01	3.54481993040582
1967-01-01	3.53384476064577
1968-01-01	3.52604731819611
1969-01-01	3.53768943121433
1970-01-01	3.56708822300710
1971-01-01	3.66748611490485
1972-01-01	3.78226535865860
1973-01-01	3.89680483592401
1974-01-01	3.99627513092756
1975-01-01	4.07556961247927
1976-01-01	4.14098426634668
1977-01-01	4.19227887420253
1978-01-01	4.23769293836666
1979-01-01	4.26590081255254
1980-01-01	4.28746624042331
1981-01-01	4.37811620255741
1982-01-01	4.44503878042257
1983-01-01	4.49836800633016
1984-01-01	4.54965207777850
1985-01-01	4.60630072700696
1986-01-01	4.67049452666553
1987-01-01	4.73915963877901
1988-01-01	4.81576178708620
1989-01-01	4.88811461868861
1990-01-01	4.94914216047165
1991-01-01	4.99458175781610
1992-01-01	5.03196732854528
1993-01-01	5.06311013337000
1994-01-01	5.10189838079285
1995-01-01	5.14701256212906
1996-01-01	5.27979263994755
1997-01-01	5.42272738652580
1998-01-01	5.57057498285826
1999-01-01	5.71909368977189
2000-01-01	5.86599395878255
2001-01-01	6.03943973461113
2002-01-01	6.20929222752931
2003-01-01	6.38281798547723
2004-01-01	6.57366427388666
2005-01-01	6.78854765649846
2006-01-01	7.25315625859116
2007-01-01	7.75541479787947
2008-01-01	8.27693140705373
2009-01-01	8.80066932618739
2010-01-01	9.31535988718795
2011-01-01	9.41266095179006
2012-01-01	9.49491820733714
2013-01-01	9.57008503602672
2014-01-01	9.65057985589291
2015-01-01	9.74168589807909
2016-01-01	9.84241428503321
2017-01-01	9.95420897359324