Year	Percent of Total
1960-01-01	40.1909925993538
1961-01-01	40.4780213851210
1962-01-01	40.7023195694625
1963-01-01	40.8606795137125
1964-01-01	40.9479720741497
1965-01-01	40.9697655619482
1966-01-01	41.0706432673752
1967-01-01	41.0965637301582
1968-01-01	41.0618563832830
1969-01-01	40.9936809727555
1970-01-01	40.9006356956705
1971-01-01	40.7120829405661
1972-01-01	40.5301401487346
1973-01-01	40.3427089597728
1974-01-01	40.1249204218228
1975-01-01	39.8682599363854
1976-01-01	39.6317729872559
1977-01-01	39.3604516951683
1978-01-01	39.0917288714262
1979-01-01	38.8733882502362
1980-01-01	38.7188273415449
1981-01-01	38.5714054898890
1982-01-01	38.4752900514190
1983-01-01	38.4133745126852
1984-01-01	38.3421343140867
1985-01-01	38.2314130273266
1986-01-01	38.1807067561918
1987-01-01	38.0496467529767
1988-01-01	37.8782967323169
1989-01-01	37.7117695024181
1990-01-01	37.5598890199199
1991-01-01	37.4093937596433
1992-01-01	37.2909736398536
1993-01-01	37.1704647832591
1994-01-01	36.9954459092351
1995-01-01	36.7578475909184
1996-01-01	36.5786691629649
1997-01-01	36.3286816208510
1998-01-01	36.0388009749456
1999-01-01	35.7294634109814
2000-01-01	35.4214076661509
2001-01-01	35.0330011613003
2002-01-01	34.6400792507547
2003-01-01	34.2441454871497
2004-01-01	33.8394885491556
2005-01-01	33.4235219088758
2006-01-01	32.8626414383791
2007-01-01	32.3127497737865
2008-01-01	31.7889803723806
2009-01-01	31.3056179704389
2010-01-01	30.8693339359707
2011-01-01	30.5991091157421
2012-01-01	30.3266329657637
2013-01-01	30.0781705440680
2014-01-01	29.8632880903640
2015-01-01	29.6716045217411
2016-01-01	29.5125662037608
2017-01-01	29.3624232338204