Year	Percent of Total
1960-01-01	44.7054685829586
1961-01-01	45.4049853243924
1962-01-01	46.1895384876674
1963-01-01	46.9384782811277
1964-01-01	47.4828431432687
1965-01-01	47.7493006557573
1966-01-01	48.0326772233035
1967-01-01	48.0936174465010
1968-01-01	47.9880117208796
1969-01-01	47.8075986057688
1970-01-01	47.5900887049556
1971-01-01	47.3679525995831
1972-01-01	47.0704737219874
1973-01-01	46.7072317031362
1974-01-01	46.2854605429511
1975-01-01	45.8184080633136
1976-01-01	45.3309127123457
1977-01-01	44.8181537166677
1978-01-01	44.2940672323111
1979-01-01	43.7801058334583
1980-01-01	43.2927434460413
1981-01-01	42.9521810608543
1982-01-01	42.6229841263316
1983-01-01	42.3021676101756
1984-01-01	41.9706265788350
1985-01-01	41.6092272676287
1986-01-01	41.3349368819882
1987-01-01	40.9707331326731
1988-01-01	40.5484641817692
1989-01-01	40.1145832731909
1990-01-01	39.6875799867005
1991-01-01	39.1651697041252
1992-01-01	38.7140582084931
1993-01-01	38.2716217835010
1994-01-01	37.7500351744970
1995-01-01	37.1117854133254
1996-01-01	36.5183714283332
1997-01-01	35.7889615146694
1998-01-01	34.9865518557892
1999-01-01	34.2169949792385
2000-01-01	33.5340557853429
2001-01-01	32.8165551772075
2002-01-01	32.2406422961383
2003-01-01	31.7523824018259
2004-01-01	31.2692795737208
2005-01-01	30.7558352312026
2006-01-01	30.2917787762656
2007-01-01	29.7768059770675
2008-01-01	29.2584879096353
2009-01-01	28.8183234850678
2010-01-01	28.4965438831330
2011-01-01	28.1894820152262
2012-01-01	28.0069841445267
2013-01-01	27.9052282663039
2014-01-01	27.8045084221198
2015-01-01	27.6594487158439
2016-01-01	27.5722879062735
2017-01-01	27.3927841345645