Year	Percent of Total
1960-01-01	42.4633057574863
1961-01-01	42.6365700336841
1962-01-01	42.8270695298831
1963-01-01	42.9956374264675
1964-01-01	43.0838497306501
1965-01-01	43.0668407374609
1966-01-01	43.1155680102940
1967-01-01	43.0302838447242
1968-01-01	42.8553870609745
1969-01-01	42.6517921357157
1970-01-01	42.4470023934639
1971-01-01	42.2480978484820
1972-01-01	42.0508674463063
1973-01-01	41.8405950881785
1974-01-01	41.5910119255065
1975-01-01	41.2936307592521
1976-01-01	41.0315443270514
1977-01-01	40.7310160885025
1978-01-01	40.4030844150551
1979-01-01	40.0654197724067
1980-01-01	39.7275761601493
1981-01-01	39.4362560255333
1982-01-01	39.1329838814218
1983-01-01	38.8209050468541
1984-01-01	38.4982036003087
1985-01-01	38.1617634495859
1986-01-01	37.8344762510248
1987-01-01	37.4910782196107
1988-01-01	37.1329776388070
1989-01-01	36.7621037878905
1990-01-01	36.3793274951218
1991-01-01	35.9896531144335
1992-01-01	35.5905714926808
1993-01-01	35.1801140685776
1994-01-01	34.7571719769311
1995-01-01	34.3226331477942
1996-01-01	33.8958117081806
1997-01-01	33.4654881754579
1998-01-01	33.0307292074014
1999-01-01	32.5902627175026
2000-01-01	32.1434256642517
2001-01-01	31.7072900288447
2002-01-01	31.2588785870378
2003-01-01	30.8041568742714
2004-01-01	30.3513567480663
2005-01-01	29.9042688583370
2006-01-01	29.4378107651408
2007-01-01	28.9800551992125
2008-01-01	28.5276332804482
2009-01-01	28.0776332060775
2010-01-01	27.6314170273427
2011-01-01	27.2002504260907
2012-01-01	26.7846624427764
2013-01-01	26.3808863279140
2014-01-01	25.9845453109878
2015-01-01	25.5938191898767
2016-01-01	25.2513278623582
2017-01-01	24.9008659662070