Year	Percent of Total
1960-01-01	58.4774723361856
1961-01-01	58.3846314415532
1962-01-01	58.5086624045949
1963-01-01	58.7664954135547
1964-01-01	59.0430647967666
1965-01-01	59.2893976917322
1966-01-01	59.3763896273155
1967-01-01	59.4403842709966
1968-01-01	59.5143207809628
1969-01-01	59.6334226870490
1970-01-01	59.7982108205864
1971-01-01	60.0428379049624
1972-01-01	60.2874164671572
1973-01-01	60.5620375131004
1974-01-01	60.9048717415193
1975-01-01	61.3401919722523
1976-01-01	61.4966367172044
1977-01-01	61.7976970323526
1978-01-01	62.2102388144799
1979-01-01	62.6453570427299
1980-01-01	63.0357536136405
1981-01-01	63.5658557115900
1982-01-01	63.9829087867515
1983-01-01	64.3325354841779
1984-01-01	64.6775120596873
1985-01-01	65.0317174157558
1986-01-01	65.2049172356111
1987-01-01	65.3768655555566
1988-01-01	65.5345128048795
1989-01-01	65.6331515101205
1990-01-01	65.6457942682124
1991-01-01	65.6256946116994
1992-01-01	65.5770855117106
1993-01-01	65.5134685046616
1994-01-01	65.4604296274176
1995-01-01	65.4371940082766
1996-01-01	65.3545308767081
1997-01-01	65.3111560131992
1998-01-01	65.3251317265922
1999-01-01	65.3859440653032
2000-01-01	65.4683248168761
2001-01-01	65.6743603331992
2002-01-01	65.8571368735312
2003-01-01	66.0313137342994
2004-01-01	66.2100000049014
2005-01-01	66.3920509847401
2006-01-01	66.4657947111708
2007-01-01	66.5205422627258
2008-01-01	66.5447809598383
2009-01-01	66.5238573908715
2010-01-01	66.4497666165835
2011-01-01	66.2151949872860
2012-01-01	66.0102651383484
2013-01-01	65.8158324233591
2014-01-01	65.6095429960365
2015-01-01	65.3819932335500
2016-01-01	65.1796363439754
2017-01-01	64.9124764281152