Year	Percent of Total
1960-01-01	8.57659990833626
1961-01-01	8.66876021664192
1962-01-01	8.76448020929714
1963-01-01	8.86083884915507
1964-01-01	8.95997537834985
1965-01-01	9.06431485535017
1966-01-01	9.20828350623256
1967-01-01	9.35079976008879
1968-01-01	9.49510124883239
1969-01-01	9.63242360439440
1970-01-01	9.76750928373454
1971-01-01	9.93160039233311
1972-01-01	10.08030605664200
1973-01-01	10.22063200144760
1974-01-01	10.35309327363520
1975-01-01	10.48467451204110
1976-01-01	10.66061589615020
1977-01-01	10.83748508754260
1978-01-01	11.00307510972930
1979-01-01	11.13140988233240
1980-01-01	11.21118385934960
1981-01-01	11.26119786959810
1982-01-01	11.25582407570050
1983-01-01	11.23015629450150
1984-01-01	11.23072121808240
1985-01-01	11.28290055439790
1986-01-01	11.40554767185710
1987-01-01	11.56551913908150
1988-01-01	11.74882402449490
1989-01-01	11.93205613090450
1990-01-01	12.10178834761300
1991-01-01	12.27821964319810
1992-01-01	12.45921361634980
1993-01-01	12.60605792508930
1994-01-01	12.74395105523020
1995-01-01	12.85874607587330
1996-01-01	13.00582055046450
1997-01-01	13.14289563266240
1998-01-01	13.27406403604660
1999-01-01	13.40432935302670
2000-01-01	13.53705233859460
2001-01-01	13.69153492251090
2002-01-01	13.84557080540010
2003-01-01	13.99948622464780
2004-01-01	14.14832396699750
2005-01-01	14.29336906279750
2006-01-01	14.44960271610090
2007-01-01	14.59638374681060
2008-01-01	14.74881060587120
2009-01-01	14.93306578917780
2010-01-01	15.16685918174620
2011-01-01	15.42749747827850
2012-01-01	15.73795133061120
2013-01-01	16.08155078734530
2014-01-01	16.43266218012920
2015-01-01	16.77755358913790
2016-01-01	17.11402134080660
2017-01-01	17.43484019691670