Year	Percent of Total
1960-01-01	41.6340682306697
1961-01-01	41.8552626772187
1962-01-01	41.8496550227971
1963-01-01	41.7384706712987
1964-01-01	41.6840706195307
1965-01-01	41.7564693143051
1966-01-01	42.1158235985881
1967-01-01	42.5219496449322
1968-01-01	42.9334227187141
1969-01-01	43.2665771721703
1970-01-01	43.4831561399223
1971-01-01	43.8797424391163
1972-01-01	44.1169149871286
1973-01-01	44.2325721205985
1974-01-01	44.2803532420978
1975-01-01	44.2913329439598
1976-01-01	44.4783075225664
1977-01-01	44.5798950992859
1978-01-01	44.6084709568031
1979-01-01	44.5729143482667
1980-01-01	44.4882114007750
1981-01-01	44.5802130934396
1982-01-01	44.5668817489224
1983-01-01	44.4807504335122
1984-01-01	44.3494813246613
1985-01-01	44.1725451084173
1986-01-01	44.2414175071803
1987-01-01	44.3360116115592
1988-01-01	44.4148863441402
1989-01-01	44.4065753030118
1990-01-01	44.2562262058244
1991-01-01	44.4139196386287
1992-01-01	44.4249755438306
1993-01-01	44.3395863895179
1994-01-01	44.3030573271391
1995-01-01	44.4794129299669
1996-01-01	44.5952452409305
1997-01-01	44.6874495829554
1998-01-01	44.7919260620175
1999-01-01	44.8579301714804
2000-01-01	44.8283571041402
2001-01-01	44.8910321427865
2002-01-01	44.8276395704682
2003-01-01	44.6666076573635
2004-01-01	44.4678532883134
2005-01-01	44.2783384185011
2006-01-01	44.1607330619479
2007-01-01	44.0228863697950
2008-01-01	43.8579763915806
2009-01-01	43.6382723135850
2010-01-01	43.3448075689825
2011-01-01	43.1812015419485
2012-01-01	42.9565000206133
2013-01-01	42.6842520100667
2014-01-01	42.3893616591352
2015-01-01	42.0843272623710
2016-01-01	41.8801003701333
2017-01-01	41.6733554850246