Year	Percent of Total
1960-01-01	43.4705486574102
1961-01-01	44.0721529043413
1962-01-01	44.8713079226060
1963-01-01	45.6623493203385
1964-01-01	46.1675251410351
1965-01-01	46.2904564315353
1966-01-01	45.9353684445936
1967-01-01	45.2637473998613
1968-01-01	44.4179737176770
1969-01-01	43.6075145770826
1970-01-01	42.9377310295332
1971-01-01	42.2903496750807
1972-01-01	41.8116038937729
1973-01-01	41.4236672051696
1974-01-01	40.9989104436235
1975-01-01	40.4877807398977
1976-01-01	40.4026773825376
1977-01-01	40.0708347399198
1978-01-01	39.6442620147084
1979-01-01	39.2468133179861
1980-01-01	38.9076509804124
1981-01-01	38.7105480170927
1982-01-01	38.5808817821936
1983-01-01	38.4809744692084
1984-01-01	38.3453926416071
1985-01-01	38.1360461801596
1986-01-01	37.2841729733474
1987-01-01	36.4520120190891
1988-01-01	35.7141103993324
1989-01-01	35.1089800170169
1990-01-01	34.6314508182468
1991-01-01	34.4014060704387
1992-01-01	34.1484069016619
1993-01-01	33.8788504743550
1994-01-01	33.5601416112598
1995-01-01	33.1570163396054
1996-01-01	32.8268225363391
1997-01-01	32.3797101635057
1998-01-01	31.8499351548452
1999-01-01	31.2667604485594
2000-01-01	30.6462890220591
2001-01-01	30.1069925937251
2002-01-01	29.5023741088083
2003-01-01	28.9216698878573
2004-01-01	28.3734281255997
2005-01-01	27.8257630943318
2006-01-01	27.5000675219446
2007-01-01	27.0986277690042
2008-01-01	26.6859502388913
2009-01-01	26.3062443325725
2010-01-01	25.9572584919544
2011-01-01	25.4148974780020
2012-01-01	24.9484675345468
2013-01-01	24.5245442624890
2014-01-01	24.1020247556497
2015-01-01	23.6666012041902
2016-01-01	23.3853817143829
2017-01-01	23.0244205114568