Year	Percent of Total
1960-01-01	44.6930932486992
1961-01-01	43.5495360018995
1962-01-01	42.2505156839035
1963-01-01	40.9370370960292
1964-01-01	39.6898844285312
1965-01-01	38.5416528112156
1966-01-01	37.4206292333672
1967-01-01	36.4986522436180
1968-01-01	35.8002991364346
1969-01-01	35.3100775193798
1970-01-01	35.0519535114799
1971-01-01	32.6077443975783
1972-01-01	30.6115518692150
1973-01-01	29.2005518991676
1974-01-01	28.4073454909582
1975-01-01	28.1643948304602
1976-01-01	27.4041144273916
1977-01-01	27.0282589488008
1978-01-01	27.1276907805346
1979-01-01	27.5273097769001
1980-01-01	28.0063776880689
1981-01-01	28.7469890266750
1982-01-01	29.5140578960863
1983-01-01	30.3291941327630
1984-01-01	31.1507662623115
1985-01-01	31.9072903097799
1986-01-01	32.0604693054969
1987-01-01	31.9901481241326
1988-01-01	31.7627392352805
1989-01-01	31.4054951957327
1990-01-01	30.9303860821622
1991-01-01	30.1905660128343
1992-01-01	29.4473073684523
1993-01-01	28.7055162056804
1994-01-01	27.9669307068450
1995-01-01	27.2577404627535
1996-01-01	26.8946954905057
1997-01-01	26.4960870515294
1998-01-01	26.2317112057347
1999-01-01	26.1019315552504
2000-01-01	25.9801104622138
2001-01-01	23.8861201575932
2002-01-01	22.0390895156066
2003-01-01	20.5140018578638
2004-01-01	19.3166665484324
2005-01-01	18.4143374410042
2006-01-01	16.7128510470749
2007-01-01	15.4137933944147
2008-01-01	14.5212450092671
2009-01-01	13.8970047583003
2010-01-01	13.3771281794831
2011-01-01	13.5486121320615
2012-01-01	13.5991168089984
2013-01-01	13.6245743656387
2014-01-01	13.6891214478175
2015-01-01	13.7865344621578
2016-01-01	13.8877225929197
2017-01-01	13.8956473543759