Year	Percent of Total
1960-01-01	3.67746846562309
1961-01-01	3.67558654064533
1962-01-01	3.66481662010260
1963-01-01	3.64639214442244
1964-01-01	3.62159037068607
1965-01-01	3.59111694494820
1966-01-01	3.57549540091579
1967-01-01	3.55331693860565
1968-01-01	3.52490348492156
1969-01-01	3.49004335409575
1970-01-01	3.44896934830080
1971-01-01	3.42360300832579
1972-01-01	3.39055388362740
1973-01-01	3.35101324421071
1974-01-01	3.30614240557580
1975-01-01	3.25699624420602
1976-01-01	3.21847915052001
1977-01-01	3.17627129353738
1978-01-01	3.13104281550467
1979-01-01	3.08296343475633
1980-01-01	3.03279429147107
1981-01-01	2.99639497311421
1982-01-01	2.95710054369646
1983-01-01	2.91648235874374
1984-01-01	2.87620411688027
1985-01-01	2.83760427148944
1986-01-01	2.80730899129313
1987-01-01	2.77701202283142
1988-01-01	2.74848361621515
1989-01-01	2.72388282925718
1990-01-01	2.70476577573505
1991-01-01	2.69611182121390
1992-01-01	2.69020695560515
1993-01-01	2.68663095923238
1994-01-01	2.68431503024316
1995-01-01	2.68249019178207
1996-01-01	2.69821364661184
1997-01-01	2.70562242035795
1998-01-01	2.70574178807969
1999-01-01	2.69976562722373
2000-01-01	2.68816539319921
2001-01-01	2.67830540691172
2002-01-01	2.66707942422729
2003-01-01	2.65128453283264
2004-01-01	2.62607216533085
2005-01-01	2.59061956007453
2006-01-01	2.56695108637714
2007-01-01	2.53525260484133
2008-01-01	2.50241797777974
2009-01-01	2.47736149857729
2010-01-01	2.46464148426830
2011-01-01	2.46999076584634
2012-01-01	2.48566504414350
2013-01-01	2.51044859298498
2014-01-01	2.54230541508009
2015-01-01	2.58038639342713
2016-01-01	2.63200321194731
2017-01-01	2.68642999451387