Year	Percent of Total
1960-01-01	47.3469022070785
1961-01-01	47.7671000874126
1962-01-01	48.2604335293513
1963-01-01	48.7355872380492
1964-01-01	49.0492822854186
1965-01-01	49.1432782418563
1966-01-01	49.1068773409121
1967-01-01	48.9450573135904
1968-01-01	48.6770986298189
1969-01-01	48.3530863804786
1970-01-01	48.0120478913271
1971-01-01	47.8108155764490
1972-01-01	47.5749223264493
1973-01-01	47.3363237567527
1974-01-01	47.1275307465610
1975-01-01	46.9588228605672
1976-01-01	46.9463673068889
1977-01-01	46.9301292686880
1978-01-01	46.9192856259647
1979-01-01	46.9138250212599
1980-01-01	46.9047142843956
1981-01-01	46.9508347969841
1982-01-01	47.0054795118650
1983-01-01	47.0429902557839
1984-01-01	47.0252010566821
1985-01-01	46.9302856144538
1986-01-01	46.8157981857386
1987-01-01	46.6171406585160
1988-01-01	46.3556085064864
1989-01-01	46.0602944567124
1990-01-01	45.7425568183875
1991-01-01	45.2833635566079
1992-01-01	44.8073859048960
1993-01-01	44.3056716471859
1994-01-01	43.7596624435240
1995-01-01	43.1604421984343
1996-01-01	42.4956799713409
1997-01-01	41.8028721608477
1998-01-01	41.0874264265880
1999-01-01	40.3609944925510
2000-01-01	39.6306911997224
2001-01-01	38.8613439200118
2002-01-01	38.0977637287610
2003-01-01	37.3500895555879
2004-01-01	36.6339322557213
2005-01-01	35.9585621103602
2006-01-01	35.2319203788624
2007-01-01	34.5691842930940
2008-01-01	33.9557594540072
2009-01-01	33.3669103115265
2010-01-01	32.7888258112147
2011-01-01	32.2144797875967
2012-01-01	31.6322075415323
2013-01-01	31.0598483251978
2014-01-01	30.5241090077032
2015-01-01	30.0342895100077
2016-01-01	29.5070771560253
2017-01-01	29.0329148908555