Year	Percent of Total
1960-01-01	2.74260591605015
1961-01-01	2.81078838253009
1962-01-01	2.88590845614466
1963-01-01	2.96600225319177
1964-01-01	3.04706095851636
1965-01-01	3.12912969199645
1966-01-01	3.29068461395324
1967-01-01	3.46351033556988
1968-01-01	3.64517717393784
1969-01-01	3.84280144425601
1970-01-01	4.06804657340144
1971-01-01	4.33340299947001
1972-01-01	4.60739432040321
1973-01-01	4.88604007541035
1974-01-01	5.17591280801412
1975-01-01	5.48741478403457
1976-01-01	5.63176348392946
1977-01-01	5.80239015084044
1978-01-01	5.99357278037406
1979-01-01	6.19440755681391
1980-01-01	6.39959539958258
1981-01-01	6.62336011957403
1982-01-01	6.83353990840479
1983-01-01	7.02448266868728
1984-01-01	7.20436289417536
1985-01-01	7.38993881545003
1986-01-01	7.65845143447794
1987-01-01	7.93862688727361
1988-01-01	8.22722677594898
1989-01-01	8.52088381903421
1990-01-01	8.82004006255169
1991-01-01	9.04075920963265
1992-01-01	9.26410249609371
1993-01-01	9.50008816124064
1994-01-01	9.75368475361044
1995-01-01	10.02123580703310
1996-01-01	10.22562365724040
1997-01-01	10.43264579239740
1998-01-01	10.63377261951030
1999-01-01	10.82319436363870
2000-01-01	11.00322735844330
2001-01-01	11.29674846696950
2002-01-01	11.58729259348080
2003-01-01	11.85888065159950
2004-01-01	12.08407612563260
2005-01-01	12.25054596960850
2006-01-01	12.40869305122630
2007-01-01	12.49641039795190
2008-01-01	12.56896833187730
2009-01-01	12.71060328167080
2010-01-01	12.97304383733980
2011-01-01	13.26825001786770
2012-01-01	13.68142993378220
2013-01-01	14.17659557413640
2014-01-01	14.69804350868840
2015-01-01	15.21776843952020
2016-01-01	15.76588734004000
2017-01-01	16.30282517726350