Year	Percent of Total
1960-01-01	41.1937679566534
1961-01-01	41.4837361891757
1962-01-01	41.7511068468871
1963-01-01	41.9970848729869
1964-01-01	42.2112924891445
1965-01-01	42.3912199109022
1966-01-01	42.6950749594830
1967-01-01	42.9343063010954
1968-01-01	43.1273863781110
1969-01-01	43.2961777070770
1970-01-01	43.4524315436852
1971-01-01	43.6790998142386
1972-01-01	43.8704655853978
1973-01-01	44.0284295881079
1974-01-01	44.1501533036449
1975-01-01	44.2350156191137
1976-01-01	44.4733357306521
1977-01-01	44.6537968033660
1978-01-01	44.7810867928615
1979-01-01	44.8584853135952
1980-01-01	44.8870204653969
1981-01-01	44.9551268924080
1982-01-01	44.9447646186055
1983-01-01	44.8722728098489
1984-01-01	44.7527527256481
1985-01-01	44.5938235805562
1986-01-01	44.4824286143893
1987-01-01	44.3328712320143
1988-01-01	44.1445424920869
1989-01-01	43.9147573397647
1990-01-01	43.6466612605754
1991-01-01	43.4162276315391
1992-01-01	43.1463290176501
1993-01-01	42.8563715330939
1994-01-01	42.5718375447246
1995-01-01	42.3085428087116
1996-01-01	42.1290890386361
1997-01-01	41.9678849068514
1998-01-01	41.8239021562740
1999-01-01	41.6878696979668
2000-01-01	41.5549734989973
2001-01-01	41.5769197594793
2002-01-01	41.5645196320711
2003-01-01	41.5424156157326
2004-01-01	41.5420147172092
2005-01-01	41.5785896725954
2006-01-01	41.5901664729925
2007-01-01	41.6232546980242
2008-01-01	41.6661179194909
2009-01-01	41.6882478174357
2010-01-01	41.6707072959061
2011-01-01	41.9495516018020
2012-01-01	42.1547157000218
2013-01-01	42.2960592819832
2014-01-01	42.3864337857088
2015-01-01	42.4278091650973
2016-01-01	42.3831031165544
2017-01-01	42.2760632989593