Year	Percent of Total
1960-01-01	43.3169545745306
1961-01-01	43.6834496583216
1962-01-01	44.0071247712508
1963-01-01	44.2766284070096
1964-01-01	44.4698271798050
1965-01-01	44.5783144331507
1966-01-01	44.7896277556600
1967-01-01	44.8871729725708
1968-01-01	44.9048166554741
1969-01-01	44.8774919036045
1970-01-01	44.8188241454907
1971-01-01	44.8731366152579
1972-01-01	44.8609680367063
1973-01-01	44.8018309268821
1974-01-01	44.7189571668052
1975-01-01	44.6307029816925
1976-01-01	44.5776054115071
1977-01-01	44.5125701632633
1978-01-01	44.4346431588405
1979-01-01	44.3328243651910
1980-01-01	44.1998113459098
1981-01-01	44.1206949116920
1982-01-01	44.0020261988203
1983-01-01	43.8546536205129
1984-01-01	43.6926585381917
1985-01-01	43.5216641662567
1986-01-01	43.4440180138839
1987-01-01	43.3338486484815
1988-01-01	43.1955042413644
1989-01-01	43.0188401814973
1990-01-01	42.8404467766580
1991-01-01	42.5810165974567
1992-01-01	42.3381407160244
1993-01-01	41.9518191133207
1994-01-01	41.5103354194361
1995-01-01	40.9571425450531
1996-01-01	40.4705780827896
1997-01-01	39.9598802351389
1998-01-01	39.4344486737201
1999-01-01	38.9013995841472
2000-01-01	38.3622114506071
2001-01-01	37.7969620603567
2002-01-01	37.2365931623866
2003-01-01	36.6865509288996
2004-01-01	36.1537897251568
2005-01-01	35.6463022430590
2006-01-01	35.1644444487679
2007-01-01	34.6982287065356
2008-01-01	34.2727681071359
2009-01-01	33.9155001190132
2010-01-01	33.6377945366603
2011-01-01	33.4796590744963
2012-01-01	33.3971277314305
2013-01-01	33.3621721394509
2014-01-01	33.3263182882363
2015-01-01	33.2572869732834
2016-01-01	33.2160835547915
2017-01-01	33.0883735668594