Year	Percent of Total
1960-01-01	53.4696813401931
1961-01-01	53.1562514746453
1962-01-01	52.7764232882199
1963-01-01	52.4039925069307
1964-01-01	52.1485396692439
1965-01-01	52.0473209447034
1966-01-01	51.6820856129765
1967-01-01	51.5142285630003
1968-01-01	51.4942104490246
1969-01-01	51.5638078598294
1970-01-01	51.7104091149280
1971-01-01	51.4849270737558
1972-01-01	51.3757859306042
1973-01-01	51.3729254517967
1974-01-01	51.4409914372607
1975-01-01	51.5371126849179
1976-01-01	51.7440226501935
1977-01-01	51.9542582763398
1978-01-01	52.1513538870981
1979-01-01	52.3351049383177
1980-01-01	52.4943664000610
1981-01-01	52.1844953879705
1982-01-01	51.9511762857036
1983-01-01	51.7328548744720
1984-01-01	51.4718377211519
1985-01-01	51.1582993518169
1986-01-01	50.7095742802172
1987-01-01	50.2706237860224
1988-01-01	49.8818136292445
1989-01-01	49.6043767982873
1990-01-01	49.4624511694856
1991-01-01	48.7551172418571
1992-01-01	48.2443727313532
1993-01-01	47.9017215586241
1994-01-01	47.6881882591938
1995-01-01	47.5888694809745
1996-01-01	47.4287184213767
1997-01-01	47.3535351287782
1998-01-01	47.3684006341702
1999-01-01	47.4724714681141
2000-01-01	47.6509466299499
2001-01-01	48.4310984926544
2002-01-01	49.2283917883211
2003-01-01	50.0094418140479
2004-01-01	50.7352712883109
2005-01-01	51.3793010079494
2006-01-01	51.8738849025281
2007-01-01	52.3061756595726
2008-01-01	52.6760464592955
2009-01-01	52.9909361857673
2010-01-01	53.2535790750012
2011-01-01	53.1486454150314
2012-01-01	53.0703315875709
2013-01-01	52.9924524379007
2014-01-01	52.8856051331458
2015-01-01	52.7448238942591
2016-01-01	52.5984175204438
2017-01-01	52.4431104048187