Year	Percent of Total
1960-01-01	10.1841575282122
1961-01-01	10.2364794646501
1962-01-01	10.2875196392948
1963-01-01	10.3383884896082
1964-01-01	10.3904832982632
1965-01-01	10.4471114361755
1966-01-01	10.6002137264575
1967-01-01	10.7561336313244
1968-01-01	10.9149041809100
1969-01-01	11.0758592132234
1970-01-01	11.2391759401870
1971-01-01	11.4791208420295
1972-01-01	11.7123258067907
1973-01-01	11.9399449701005
1974-01-01	12.1646184818884
1975-01-01	12.3883587403450
1976-01-01	12.7183909945037
1977-01-01	13.0410565476683
1978-01-01	13.3450815347855
1979-01-01	13.6079076019351
1980-01-01	13.8149568263265
1981-01-01	13.9040460071999
1982-01-01	13.9290280543489
1983-01-01	13.9215896893491
1984-01-01	13.9291427609653
1985-01-01	13.9798588153075
1986-01-01	14.0742207602425
1987-01-01	14.2050484936287
1988-01-01	14.3498908899914
1989-01-01	14.4751558167168
1990-01-01	14.5631763220068
1991-01-01	14.6389689825160
1992-01-01	14.6745241935295
1993-01-01	14.6803645017122
1994-01-01	14.6766039438533
1995-01-01	14.6772576859098
1996-01-01	14.8015492610081
1997-01-01	14.9314169321741
1998-01-01	15.0627388660807
1999-01-01	15.1858999358966
2000-01-01	15.2974571837176
2001-01-01	15.4005485454383
2002-01-01	15.4891954818900
2003-01-01	15.5767507833700
2004-01-01	15.6816015576991
2005-01-01	15.8141739857507
2006-01-01	15.9816996990005
2007-01-01	16.1733611027414
2008-01-01	16.3905764929187
2009-01-01	16.6342409056759
2010-01-01	16.9042633074101
2011-01-01	17.1090286379500
2012-01-01	17.3361704352893
2013-01-01	17.5752403207112
2014-01-01	17.8013492467279
2015-01-01	17.9965813954690
2016-01-01	18.2310471677352
2017-01-01	18.4359376852656