Year	Percent of Total
1960-01-01	42.6302763237773
1961-01-01	41.5996934391213
1962-01-01	40.6889983186973
1963-01-01	39.9411306401250
1964-01-01	39.3093020433191
1965-01-01	38.6924816218976
1966-01-01	38.5495089044130
1967-01-01	38.1468129438698
1968-01-01	37.5969488363128
1969-01-01	37.0311668677697
1970-01-01	36.5200393676234
1971-01-01	35.8249595498277
1972-01-01	35.1548138230318
1973-01-01	34.5646199579688
1974-01-01	34.0536132558341
1975-01-01	33.5969406723181
1976-01-01	33.2058021493613
1977-01-01	32.8656726640951
1978-01-01	32.4894490186940
1979-01-01	32.0480015691449
1980-01-01	31.5558600620955
1981-01-01	31.2572164421895
1982-01-01	30.9380460918748
1983-01-01	30.5528338278842
1984-01-01	30.0965978491003
1985-01-01	29.5856964417085
1986-01-01	29.1078876006612
1987-01-01	28.6239663371661
1988-01-01	28.1247930052328
1989-01-01	27.6302332051293
1990-01-01	27.1669639494311
1991-01-01	26.7509426067840
1992-01-01	26.3717213846017
1993-01-01	26.0194727366781
1994-01-01	25.6623809404027
1995-01-01	25.2754942825061
1996-01-01	25.0240366260105
1997-01-01	24.7035588420651
1998-01-01	24.3228515579402
1999-01-01	23.9297782296667
2000-01-01	23.5609538851565
2001-01-01	23.2827540252959
2002-01-01	23.0374486173442
2003-01-01	22.8059910204401
2004-01-01	22.5521461280562
2005-01-01	22.2610405962290
2006-01-01	21.9777940104599
2007-01-01	21.6844340229698
2008-01-01	21.3598041430617
2009-01-01	21.0016769846801
2010-01-01	20.6191633261074
2011-01-01	20.2662595792159
2012-01-01	19.8756158088434
2013-01-01	19.4599052300756
2014-01-01	19.0492608093808
2015-01-01	18.6665153217658
2016-01-01	18.2685583560961
2017-01-01	17.9365411720192