Year	Percent of Total
1960-01-01	8.90979391145827
1961-01-01	9.01599823959226
1962-01-01	9.13136755287750
1963-01-01	9.25380276468829
1964-01-01	9.37579537751507
1965-01-01	9.49588777062434
1966-01-01	9.61570817222854
1967-01-01	9.73173264386045
1968-01-01	9.84495136339344
1969-01-01	9.95965229734998
1970-01-01	10.07965501771540
1971-01-01	10.20059276242070
1972-01-01	10.31804923203830
1973-01-01	10.43376524865790
1974-01-01	10.54805927960740
1975-01-01	10.66138986593210
1976-01-01	10.82793510673080
1977-01-01	10.98612336055850
1978-01-01	11.13383380792130
1979-01-01	11.26497155756800
1980-01-01	11.37742284206390
1981-01-01	11.51322614135230
1982-01-01	11.61817970304330
1983-01-01	11.71094265834160
1984-01-01	11.81704790287190
1985-01-01	11.95053117521630
1986-01-01	12.09852453675740
1987-01-01	12.26769093233790
1988-01-01	12.44257663341600
1989-01-01	12.59979466871750
1990-01-01	12.72813884355480
1991-01-01	12.84183052907300
1992-01-01	12.92594512596780
1993-01-01	12.99146070547790
1994-01-01	13.05528228031270
1995-01-01	13.12852056824180
1996-01-01	13.22334563046100
1997-01-01	13.31985774944550
1998-01-01	13.41593012976860
1999-01-01	13.50430926720890
2000-01-01	13.58208254228820
2001-01-01	13.69804834701510
2002-01-01	13.80132219308640
2003-01-01	13.90091853249850
2004-01-01	14.00848839289690
2005-01-01	14.13366327862170
2006-01-01	14.32878461130270
2007-01-01	14.53549924347500
2008-01-01	14.77325907942030
2009-01-01	15.06880466058490
2010-01-01	15.43747415395040
2011-01-01	15.88943467892280
2012-01-01	16.39610115971110
2013-01-01	16.92886553376040
2014-01-01	17.44525960610930
2015-01-01	17.92018879594940
2016-01-01	18.36837219268710
2017-01-01	18.77858442546570