Year	Percent of Total
1960-01-01	3.54536677369378
1961-01-01	3.54694810140355
1962-01-01	3.52831940575673
1963-01-01	3.49251166216548
1964-01-01	3.45237387842415
1965-01-01	3.41679108763064
1966-01-01	3.39674163729958
1967-01-01	3.37896624584954
1968-01-01	3.35427974590346
1969-01-01	3.34718298155227
1970-01-01	3.32242678777816
1971-01-01	3.46493205384170
1972-01-01	3.62772480657485
1973-01-01	3.80638946861455
1974-01-01	4.00313720468660
1975-01-01	4.21417711896617
1976-01-01	4.12201410244463
1977-01-01	4.01028666515392
1978-01-01	3.88877488200287
1979-01-01	3.74911410347271
1980-01-01	3.59629406282550
1981-01-01	3.61241419522409
1982-01-01	3.61521413289947
1983-01-01	3.60445226703686
1984-01-01	3.59202306583373
1985-01-01	3.58051490325141
1986-01-01	3.58393596215946
1987-01-01	3.58586980670962
1988-01-01	3.59157148911662
1989-01-01	3.58695305608400
1990-01-01	3.57309692622313
1991-01-01	3.60327533679491
1992-01-01	3.59815802707740
1993-01-01	3.56283795485597
1994-01-01	3.52640561207652
1995-01-01	3.52932425899067
1996-01-01	3.58949272686997
1997-01-01	3.66537022359035
1998-01-01	3.72881982298269
1999-01-01	3.75547228611709
2000-01-01	3.72142378434731
2001-01-01	3.80907945691224
2002-01-01	3.88099043773310
2003-01-01	3.93012282804074
2004-01-01	3.97177627443069
2005-01-01	4.00297562996723
2006-01-01	3.97127285114114
2007-01-01	3.92280020556158
2008-01-01	3.88502842703727
2009-01-01	3.85340515582917
2010-01-01	3.84400092649784
2011-01-01	3.90265589360962
2012-01-01	3.97862863878342
2013-01-01	4.07706698038611
2014-01-01	4.20035571792530
2015-01-01	4.35207262072333
2016-01-01	4.57036126437768
2017-01-01	4.81031607670734