Year	Percent of Total
1960-01-01	8.39666599416577
1961-01-01	8.50784303604488
1962-01-01	8.62073565967469
1963-01-01	8.73786518939709
1964-01-01	8.86155785102581
1965-01-01	8.99613005222188
1966-01-01	9.16936987183079
1967-01-01	9.34355817422375
1968-01-01	9.51959534287376
1969-01-01	9.69743740751290
1970-01-01	9.87336571635754
1971-01-01	10.07867352103540
1972-01-01	10.26542156604890
1973-01-01	10.43927949863850
1974-01-01	10.61019835152820
1975-01-01	10.78170264812030
1976-01-01	10.98825352644750
1977-01-01	11.19915605035020
1978-01-01	11.38324817957520
1979-01-01	11.49299854565660
1980-01-01	11.50625826217050
1981-01-01	11.46617841434180
1982-01-01	11.33286271712380
1983-01-01	11.15946723981310
1984-01-01	11.01942030789580
1985-01-01	10.95498506287570
1986-01-01	11.00556160464340
1987-01-01	11.11061263949100
1988-01-01	11.25850711878900
1989-01-01	11.42861619165840
1990-01-01	11.61151743277600
1991-01-01	11.84213833346260
1992-01-01	12.08430126634470
1993-01-01	12.32025332813590
1994-01-01	12.52630080984350
1995-01-01	12.69137465870770
1996-01-01	12.87607993553390
1997-01-01	13.00570559962020
1998-01-01	13.10929324112450
1999-01-01	13.22794349586520
2000-01-01	13.37940195395800
2001-01-01	13.60006078511440
2002-01-01	13.84583858806190
2003-01-01	14.08592901674860
2004-01-01	14.27104238569120
2005-01-01	14.37732500565150
2006-01-01	14.48518421305100
2007-01-01	14.52916733193110
2008-01-01	14.54471761005890
2009-01-01	14.57876128190300
2010-01-01	14.66008882651010
2011-01-01	14.79298064748250
2012-01-01	14.97048960975570
2013-01-01	15.17524292830910
2014-01-01	15.39366497058500
2015-01-01	15.62109758363800
2016-01-01	15.88457523121360
2017-01-01	16.15665574802730