Year	Percent of Total
1960-01-01	41.6323123290581
1961-01-01	41.8721254801329
1962-01-01	42.0833504569638
1963-01-01	42.2641410536474
1964-01-01	42.4030711788384
1965-01-01	42.4963116309257
1966-01-01	42.6872052328794
1967-01-01	42.8137501130537
1968-01-01	42.9048660633214
1969-01-01	43.0010403796529
1970-01-01	43.1263326772461
1971-01-01	43.3590704302767
1972-01-01	43.6188951353984
1973-01-01	43.8854076550773
1974-01-01	44.1226860130452
1975-01-01	44.3123030727013
1976-01-01	44.9201781557580
1977-01-01	45.4493448645323
1978-01-01	45.9107783702891
1979-01-01	46.3203144388868
1980-01-01	46.6765151993933
1981-01-01	46.8871584044306
1982-01-01	47.0192149311886
1983-01-01	47.0801910310143
1984-01-01	47.0882847402469
1985-01-01	47.0640127771266
1986-01-01	46.3562088217749
1987-01-01	45.6714740888771
1988-01-01	45.0084859538466
1989-01-01	44.3488024777691
1990-01-01	43.6839255470449
1991-01-01	43.4059246523940
1992-01-01	43.0826420456610
1993-01-01	42.7345041580581
1994-01-01	42.3865917976894
1995-01-01	42.0459247812710
1996-01-01	41.8115792132267
1997-01-01	41.5372650503640
1998-01-01	41.2314712636822
1999-01-01	40.8904104428210
2000-01-01	40.5039444372194
2001-01-01	40.4410228403451
2002-01-01	40.3595143483133
2003-01-01	40.2365928614396
2004-01-01	40.0528461677819
2005-01-01	39.8095951374769
2006-01-01	39.5579875606474
2007-01-01	39.2661719349108
2008-01-01	38.9541273514925
2009-01-01	38.6646482985812
2010-01-01	38.4302654647359
2011-01-01	38.0470757408420
2012-01-01	37.7386001535380
2013-01-01	37.4883445858443
2014-01-01	37.2581181210228
2015-01-01	37.0240121769768
2016-01-01	36.8926565292032
2017-01-01	36.6952483114255