Year	Percent of Total
1960-01-01	2.31479267301162
1961-01-01	2.31078668444485
1962-01-01	2.31624984077109
1963-01-01	2.32837778749453
1964-01-01	2.34702508760678
1965-01-01	2.36945799953028
1966-01-01	2.36599221916560
1967-01-01	2.36535080709605
1968-01-01	2.37501957824892
1969-01-01	2.38779880843569
1970-01-01	2.40825759900788
1971-01-01	2.40417542450936
1972-01-01	2.40648573851716
1973-01-01	2.42065824272701
1974-01-01	2.43394856248873
1975-01-01	2.44844613552321
1976-01-01	2.39181512415713
1977-01-01	2.35080852965450
1978-01-01	2.32623827952521
1979-01-01	2.32619724176920
1980-01-01	2.35318698462224
1981-01-01	2.37746608096827
1982-01-01	2.41128971555087
1983-01-01	2.45351724978543
1984-01-01	2.49053611055695
1985-01-01	2.51472581899519
1986-01-01	2.52222351830373
1987-01-01	2.52217894071340
1988-01-01	2.52495751409738
1989-01-01	2.54352113275542
1990-01-01	2.58706838437800
1991-01-01	2.62242025957248
1992-01-01	2.66773323968302
1993-01-01	2.71885787273947
1994-01-01	2.76653930323957
1995-01-01	2.80271832585646
1996-01-01	2.85265084311819
1997-01-01	2.89249008628450
1998-01-01	2.92751229775555
1999-01-01	2.96415221275848
2000-01-01	3.00773149903008
2001-01-01	3.06137071778641
2002-01-01	3.11837913969186
2003-01-01	3.17829201900832
2004-01-01	3.23930395250353
2005-01-01	3.30110028164555
2006-01-01	3.36834093603682
2007-01-01	3.43512865053459
2008-01-01	3.50441226149363
2009-01-01	3.57858132976435
2010-01-01	3.65918420576493
2011-01-01	3.75223601716984
2012-01-01	3.84845407037115
2013-01-01	3.94317756008779
2014-01-01	4.02767484794401
2015-01-01	4.10032628362306
2016-01-01	4.16158619086883
2017-01-01	4.21281420293944