Year	Percent of Total
1960-01-01	3.97802437240285
1961-01-01	3.81094018682902
1962-01-01	3.60224733051900
1963-01-01	3.34855166181031
1964-01-01	3.03525820718869
1965-01-01	2.63905179332058
1966-01-01	2.98048832175348
1967-01-01	3.35774166457944
1968-01-01	3.80607029666220
1969-01-01	4.31472432552152
1970-01-01	4.86040968041695
1971-01-01	4.62309838395536
1972-01-01	4.41595625314366
1973-01-01	4.23679481663334
1974-01-01	4.08454196107599
1975-01-01	3.93429128282107
1976-01-01	4.13500618483831
1977-01-01	4.31068005581353
1978-01-01	4.47779418130959
1979-01-01	4.66383878940949
1980-01-01	4.85313168121834
1981-01-01	4.78287777204745
1982-01-01	4.74439243814966
1983-01-01	4.72497458083295
1984-01-01	4.70097630378256
1985-01-01	4.66931701951097
1986-01-01	4.70258073079622
1987-01-01	4.71349439091374
1988-01-01	4.70539873938065
1989-01-01	4.69868401014092
1990-01-01	4.69475735997822
1991-01-01	4.69241749359382
1992-01-01	4.69128736870455
1993-01-01	4.68753860980009
1994-01-01	4.67682479249514
1995-01-01	4.65861103642431
1996-01-01	4.66771722001848
1997-01-01	4.66641750631164
1998-01-01	4.65529388838088
1999-01-01	4.65022150920625
2000-01-01	4.63904881462563
2001-01-01	4.61792659332590
2002-01-01	4.59386150777492
2003-01-01	4.55476774593589
2004-01-01	4.48315116898841
2005-01-01	4.37704812696781
2006-01-01	4.25851074512954
2007-01-01	4.11769394424314
2008-01-01	3.95655221582501
2009-01-01	3.79479313635379
2010-01-01	3.63379411360827
2011-01-01	3.49664429530201
2012-01-01	3.35832116748410
2013-01-01	3.22703092838622
2014-01-01	3.10666820030743
2015-01-01	3.00276651342603
2016-01-01	2.93732179480766
2017-01-01	2.88606008995385