Year	Percent of Total
1960-01-01	8.64108782240644
1961-01-01	8.44572412191209
1962-01-01	8.23169982139112
1963-01-01	8.01841813941834
1964-01-01	7.82769204702448
1965-01-01	7.67236392093278
1966-01-01	7.65676806637726
1967-01-01	7.66542030900264
1968-01-01	7.68999663640886
1969-01-01	7.71702447402319
1970-01-01	7.74027320857773
1971-01-01	7.89917079029748
1972-01-01	8.03024898040074
1973-01-01	8.14655672976425
1974-01-01	8.26902135852717
1975-01-01	8.40933606012288
1976-01-01	8.60152251581014
1977-01-01	8.81287794962052
1978-01-01	9.01547593270589
1979-01-01	9.16644719964425
1980-01-01	9.24621020531235
1981-01-01	9.23926374295344
1982-01-01	9.16731327452839
1983-01-01	9.05945356693290
1984-01-01	8.95623024718360
1985-01-01	8.88451006161252
1986-01-01	8.88559827114091
1987-01-01	8.89965663192940
1988-01-01	8.95283677906465
1989-01-01	9.08266164980367
1990-01-01	9.30976650034416
1991-01-01	9.70981346947082
1992-01-01	10.18128056056470
1993-01-01	10.66795474955590
1994-01-01	11.08398852393480
1995-01-01	11.37888563505500
1996-01-01	11.70060211510670
1997-01-01	11.89564635929170
1998-01-01	12.02401316757530
1999-01-01	12.17809384080050
2000-01-01	12.40899361909710
2001-01-01	12.82018902597980
2002-01-01	13.29615038660460
2003-01-01	13.77304446611790
2004-01-01	14.14523410941500
2005-01-01	14.34856249137700
2006-01-01	14.50615198013200
2007-01-01	14.52431195742660
2008-01-01	14.45146819017290
2009-01-01	14.36407805030950
2010-01-01	14.31208690866300
2011-01-01	14.29188234910540
2012-01-01	14.31475716815100
2013-01-01	14.38274702106570
2014-01-01	14.48667024351100
2015-01-01	14.61547494080760
2016-01-01	14.73027623901230
2017-01-01	14.86387865628880