Year	Percent of Total
1960-01-01	43.0592855020779
1961-01-01	43.2653711299515
1962-01-01	43.3849484793180
1963-01-01	43.4446451164918
1964-01-01	43.4948057591978
1965-01-01	43.5593447258356
1966-01-01	43.6862401623178
1967-01-01	43.8100610182890
1968-01-01	43.9218308587773
1969-01-01	44.0084386100997
1970-01-01	44.0647596921737
1971-01-01	44.2000734029871
1972-01-01	44.3109983834105
1973-01-01	44.3992412905339
1974-01-01	44.4685479888420
1975-01-01	44.5238498741999
1976-01-01	44.5685978827233
1977-01-01	44.5736245239714
1978-01-01	44.5466770472079
1979-01-01	44.4932609467025
1980-01-01	44.4143962604895
1981-01-01	44.5543242861077
1982-01-01	44.6563898976728
1983-01-01	44.7121782650650
1984-01-01	44.7100703641351
1985-01-01	44.6413239577446
1986-01-01	44.5621294239933
1987-01-01	44.4461998348039
1988-01-01	44.3168961117540
1989-01-01	44.1906902314815
1990-01-01	44.0639226703277
1991-01-01	43.6820173788342
1992-01-01	43.3252295424267
1993-01-01	42.9854348662226
1994-01-01	42.6394005046595
1995-01-01	42.2723590136934
1996-01-01	42.1115296879660
1997-01-01	41.9397244777964
1998-01-01	41.7511513691382
1999-01-01	41.5348708773231
2000-01-01	41.2757217722062
2001-01-01	41.0030462020568
2002-01-01	40.6408622770608
2003-01-01	40.2254421960933
2004-01-01	39.8069945721425
2005-01-01	39.4121596702407
2006-01-01	38.8917321492708
2007-01-01	38.4473085885142
2008-01-01	38.0527818473647
2009-01-01	37.6662841736541
2010-01-01	37.2744910565823
2011-01-01	36.9274564158115
2012-01-01	36.5766189074456
2013-01-01	36.2349169555876
2014-01-01	35.9232169112935
2015-01-01	35.6522099009264
2016-01-01	35.5316969935399
2017-01-01	35.3912684102145