Year	Percent of Total
1960-01-01	53.2335798092224
1961-01-01	53.0553495371638
1962-01-01	52.9573463669736
1963-01-01	52.9011820462869
1964-01-01	52.8528003995379
1965-01-01	52.8000355105205
1966-01-01	52.6549069589193
1967-01-01	52.5584396534565
1968-01-01	52.4869855810298
1969-01-01	52.4178213267024
1970-01-01	52.3347569875826
1971-01-01	52.3513381589951
1972-01-01	52.3849941835132
1973-01-01	52.4258742242998
1974-01-01	52.4791148853419
1975-01-01	52.5437212929363
1976-01-01	52.7232003937271
1977-01-01	52.9469104684822
1978-01-01	53.1662680418072
1979-01-01	53.3315373259964
1980-01-01	53.4259238061232
1981-01-01	53.8359940582604
1982-01-01	54.1910992679271
1983-01-01	54.5077936731017
1984-01-01	54.8384789483224
1985-01-01	55.2103685501264
1986-01-01	55.1329395345537
1987-01-01	55.1624573341246
1988-01-01	55.1937374989467
1989-01-01	55.1911392932090
1990-01-01	55.2022118214728
1991-01-01	55.0209158511152
1992-01-01	54.8807103445899
1993-01-01	54.8589985862064
1994-01-01	55.0188219270399
1995-01-01	55.3644642906609
1996-01-01	56.2189067728757
1997-01-01	57.0725724787620
1998-01-01	57.8082297470464
1999-01-01	58.3690205074245
2000-01-01	58.8011873449021
2001-01-01	59.7629967753794
2002-01-01	60.6691049902156
2003-01-01	61.5313862901590
2004-01-01	62.3699668817580
2005-01-01	63.1862822075480
2006-01-01	64.0443047711068
2007-01-01	64.9166189784493
2008-01-01	65.7608274542352
2009-01-01	66.5360025612970
2010-01-01	67.2322789782830
2011-01-01	68.2038046576920
2012-01-01	69.0728715184236
2013-01-01	69.8254896829719
2014-01-01	70.4495852417291
2015-01-01	70.9481726229725
2016-01-01	71.3014970060901
2017-01-01	71.5398494751370