Year	Percent of Total
1960-01-01	43.6448327110596
1961-01-01	44.0283949087433
1962-01-01	44.3183074647907
1963-01-01	44.5579704162251
1964-01-01	44.7879491596963
1965-01-01	45.0222316798638
1966-01-01	45.3391962342855
1967-01-01	45.6322269166620
1968-01-01	45.8997023235830
1969-01-01	46.1225159656071
1970-01-01	46.2915071036621
1971-01-01	46.2191560977498
1972-01-01	46.0804783206227
1973-01-01	45.9239322371625
1974-01-01	45.8219509993491
1975-01-01	45.8193695552603
1976-01-01	45.4884903481523
1977-01-01	45.2885433541145
1978-01-01	45.1790278853602
1979-01-01	45.1129410277757
1980-01-01	45.0792157514993
1981-01-01	45.2664168961328
1982-01-01	45.3842343798324
1983-01-01	45.4694999695099
1984-01-01	45.5457672787698
1985-01-01	45.5943172027546
1986-01-01	45.6496187191140
1987-01-01	45.6781556970215
1988-01-01	45.6587625646856
1989-01-01	45.5327482827540
1990-01-01	45.2490398198834
1991-01-01	44.2588359416212
1992-01-01	43.1914956912222
1993-01-01	42.0422940662928
1994-01-01	40.8277587147440
1995-01-01	39.5716883902838
1996-01-01	39.2268224223018
1997-01-01	38.7255514222990
1998-01-01	38.1786733277824
1999-01-01	37.6419009471741
2000-01-01	37.1043359519504
2001-01-01	36.3566204619427
2002-01-01	35.4989643509683
2003-01-01	34.5376070902272
2004-01-01	33.5110610446626
2005-01-01	32.4770862858579
2006-01-01	30.5679733301432
2007-01-01	28.8928563649323
2008-01-01	27.5315021960744
2009-01-01	26.4786804590588
2010-01-01	25.6890769564617
2011-01-01	24.5459751864844
2012-01-01	23.6323847414049
2013-01-01	22.9769194561416
2014-01-01	22.5235267014649
2015-01-01	22.1722887463957
2016-01-01	22.0343602661567
2017-01-01	21.8125722834473