Year	Percent of Total
1960-01-01	53.9688707435136
1961-01-01	53.5524967784852
1962-01-01	53.4964423148163
1963-01-01	53.6622753468517
1964-01-01	53.8511092809302
1965-01-01	53.9697351635726
1966-01-01	53.8798091313870
1967-01-01	53.7646207334777
1968-01-01	53.6594871376346
1969-01-01	53.6458817074383
1970-01-01	53.7629892913292
1971-01-01	53.7002171183967
1972-01-01	53.7796846029091
1973-01-01	53.9585409938581
1974-01-01	54.1632928450383
1975-01-01	54.3510308412573
1976-01-01	54.4269315357877
1977-01-01	54.4758620146692
1978-01-01	54.5160078091345
1979-01-01	54.5757005189387
1980-01-01	54.6620702960616
1981-01-01	54.6462767379682
1982-01-01	54.6750339912229
1983-01-01	54.7212647597763
1984-01-01	54.7451755205468
1985-01-01	54.7298261318074
1986-01-01	54.6541414563636
1987-01-01	54.5530152519411
1988-01-01	54.4556104119258
1989-01-01	54.4200428046187
1990-01-01	54.4864607644906
1991-01-01	54.4666387188674
1992-01-01	54.6292865612127
1993-01-01	54.9261605773561
1994-01-01	55.2865255066565
1995-01-01	55.6756255957642
1996-01-01	56.2241365991670
1997-01-01	56.7403268489027
1998-01-01	57.2682209768712
1999-01-01	57.8651965364366
2000-01-01	58.5399093422440
2001-01-01	59.1803606893684
2002-01-01	59.8560536848831
2003-01-01	60.5378999107647
2004-01-01	61.1852442189072
2005-01-01	61.7741969788826
2006-01-01	62.1671556183745
2007-01-01	62.5713487992853
2008-01-01	62.9215701221292
2009-01-01	63.1256413173576
2010-01-01	63.1387189881495
2011-01-01	63.0839902427497
2012-01-01	62.7765600358042
2013-01-01	62.3494171133919
2014-01-01	61.9930304529339
2015-01-01	61.7999154430095
2016-01-01	61.4386982719513
2017-01-01	61.3696783612864