Year	Percent of Total
1960-01-01	56.2216185591259
1961-01-01	55.8526631010110
1962-01-01	55.4904162377053
1963-01-01	55.1688657871957
1964-01-01	54.9418955922033
1965-01-01	54.8306514868195
1966-01-01	54.6258554282347
1967-01-01	54.5508030454761
1968-01-01	54.5732101175919
1969-01-01	54.6473788693016
1970-01-01	54.7486810703720
1971-01-01	54.7495775653023
1972-01-01	54.7952059514137
1973-01-01	54.8801164345051
1974-01-01	55.0046203262048
1975-01-01	55.1651490946175
1976-01-01	55.1988719303840
1977-01-01	55.2930512857799
1978-01-01	55.4296200585428
1979-01-01	55.5876401679407
1980-01-01	55.7540397452194
1981-01-01	55.8120650298816
1982-01-01	55.8921509985811
1983-01-01	55.9946607288606
1984-01-01	56.1268116549069
1985-01-01	56.2917851681612
1986-01-01	56.3399106319125
1987-01-01	56.4529714887066
1988-01-01	56.6150171584556
1989-01-01	56.8079505751510
1990-01-01	57.0159585044469
1991-01-01	57.1617268811883
1992-01-01	57.3426102431375
1993-01-01	57.5621250272401
1994-01-01	57.8280093609900
1995-01-01	58.1424954785673
1996-01-01	58.4111943360198
1997-01-01	58.7274968143595
1998-01-01	59.0825576563443
1999-01-01	59.4597192618002
2000-01-01	59.8444054687139
2001-01-01	60.1274035532922
2002-01-01	60.4244335943052
2003-01-01	60.7321726388732
2004-01-01	61.0478748383429
2005-01-01	61.3687924357693
2006-01-01	61.6352079968873
2007-01-01	61.9078066151777
2008-01-01	62.1828560433680
2009-01-01	62.4575068641590
2010-01-01	62.7298228481100
2011-01-01	62.9497454538914
2012-01-01	63.1771022519187
2013-01-01	63.4050505346818
2014-01-01	63.6243008877032
2015-01-01	63.8301326994241
2016-01-01	63.9860268147135
2017-01-01	64.1322747194057