Year	Percent of Total
1960-01-01	39.9493418810618
1961-01-01	40.1998134045608
1962-01-01	40.4324729134977
1963-01-01	40.6441134337572
1964-01-01	40.8204216696338
1965-01-01	40.9578572177740
1966-01-01	41.3086591775015
1967-01-01	41.5710619342386
1968-01-01	41.7770810024416
1969-01-01	41.9624800988095
1970-01-01	42.1437013558509
1971-01-01	42.4966313289025
1972-01-01	42.8032495795049
1973-01-01	43.0711654514494
1974-01-01	43.3006114300869
1975-01-01	43.4935168763431
1976-01-01	43.8197548844799
1977-01-01	44.0809867584070
1978-01-01	44.2945663844352
1979-01-01	44.4801840084114
1980-01-01	44.6493147067294
1981-01-01	44.9390049505708
1982-01-01	45.1921949353207
1983-01-01	45.4084450793716
1984-01-01	45.5819761794565
1985-01-01	45.7110496165034
1986-01-01	45.9702169111619
1987-01-01	46.1431522790085
1988-01-01	46.2491627625803
1989-01-01	46.3047037677979
1990-01-01	46.3123178757749
1991-01-01	46.4051136544068
1992-01-01	46.4314291053758
1993-01-01	46.3905651287131
1994-01-01	46.2760361443394
1995-01-01	46.0864925725396
1996-01-01	45.9808859703028
1997-01-01	45.7944602148485
1998-01-01	45.5442704514111
1999-01-01	45.2587586089638
2000-01-01	44.9618946521312
2001-01-01	44.7825656666216
2002-01-01	44.5925634785351
2003-01-01	44.3969300383642
2004-01-01	44.1958735853670
2005-01-01	43.9927798932253
2006-01-01	43.9237842803081
2007-01-01	43.8185623582084
2008-01-01	43.6963162019078
2009-01-01	43.5752174664137
2010-01-01	43.4599693197390
2011-01-01	43.4312420192406
2012-01-01	43.3793371460902
2013-01-01	43.3021352562130
2014-01-01	43.1898671864771
2015-01-01	43.0365960802683
2016-01-01	42.9044196025724
2017-01-01	42.7251169849895