Year	Percent of Total
1960-01-01	41.4529639586263
1961-01-01	41.5237703856621
1962-01-01	42.1328256945361
1963-01-01	42.9705913893852
1964-01-01	43.6125118333102
1965-01-01	43.9095498181486
1966-01-01	44.3475583170080
1967-01-01	44.4760960832885
1968-01-01	44.4418888371288
1969-01-01	44.4579334616929
1970-01-01	44.6086064071697
1971-01-01	45.0108878759871
1972-01-01	45.3666633804551
1973-01-01	45.7047404815159
1974-01-01	46.0228485706494
1975-01-01	46.3041960654329
1976-01-01	46.4873293112923
1977-01-01	46.7051132846274
1978-01-01	46.8846094444912
1979-01-01	46.9383568117151
1980-01-01	46.8382132568725
1981-01-01	46.8777506773910
1982-01-01	46.7781926540012
1983-01-01	46.5843875155649
1984-01-01	46.3724740145030
1985-01-01	46.1789907099814
1986-01-01	46.1111451004385
1987-01-01	46.0689647467313
1988-01-01	46.0285181061731
1989-01-01	45.9605027878210
1990-01-01	45.8573112778891
1991-01-01	45.5570018249746
1992-01-01	45.2234555864018
1993-01-01	44.8796615301866
1994-01-01	44.5579757434198
1995-01-01	44.2741471647391
1996-01-01	43.9621703901099
1997-01-01	43.6999294862857
1998-01-01	43.4653552799090
1999-01-01	43.2217264363439
2000-01-01	42.9505648808277
2001-01-01	42.8077859777700
2002-01-01	42.6117510359854
2003-01-01	42.3917767490442
2004-01-01	42.1916174686488
2005-01-01	42.0296465999166
2006-01-01	41.9020682858693
2007-01-01	41.8394781086995
2008-01-01	41.8056908737902
2009-01-01	41.7589774920277
2010-01-01	41.6885630426275
2011-01-01	41.5177325167894
2012-01-01	41.3083998323071
2013-01-01	41.0835593921402
2014-01-01	40.8667608598278
2015-01-01	40.6610995693308
2016-01-01	40.5362484077714
2017-01-01	40.3987284732665