Year	Percent of Total
1960-01-01	4.97397993376629
1961-01-01	5.02066579033091
1962-01-01	5.04572211838550
1963-01-01	5.05473902938605
1964-01-01	5.05873247348376
1965-01-01	5.05981247436414
1966-01-01	5.11655179742598
1967-01-01	5.17109394124404
1968-01-01	5.22168415338354
1969-01-01	5.26754042655115
1970-01-01	5.30716287167390
1971-01-01	5.37427573843697
1972-01-01	5.43303315690799
1973-01-01	5.48481989737335
1974-01-01	5.53471434239752
1975-01-01	5.58418837722399
1976-01-01	5.66315267441034
1977-01-01	5.74068802498511
1978-01-01	5.81078362630068
1979-01-01	5.86367216048960
1980-01-01	5.89490147730395
1981-01-01	5.92822338583398
1982-01-01	5.93534131544512
1983-01-01	5.92949621213587
1984-01-01	5.92654658472836
1985-01-01	5.93467357412264
1986-01-01	5.97130066990722
1987-01-01	6.01204010012008
1988-01-01	6.05719446787226
1989-01-01	6.10652506315315
1990-01-01	6.15875171113031
1991-01-01	6.23257169450685
1992-01-01	6.31273253028196
1993-01-01	6.39085805209618
1994-01-01	6.46219777923779
1995-01-01	6.52424817224058
1996-01-01	6.61305633308908
1997-01-01	6.68642002607554
1998-01-01	6.75138996307769
1999-01-01	6.81757982335536
2000-01-01	6.88862866697195
2001-01-01	6.98141386087520
2002-01-01	7.07497971987550
2003-01-01	7.16517863332612
2004-01-01	7.24300779598325
2005-01-01	7.30553841175182
2006-01-01	7.37813378921098
2007-01-01	7.43838304384080
2008-01-01	7.49488883207890
2009-01-01	7.55815747432513
2010-01-01	7.63587297852275
2011-01-01	7.73653865070551
2012-01-01	7.84836970246791
2013-01-01	7.97349184254478
2014-01-01	8.11733085812263
2015-01-01	8.28337228113954
2016-01-01	8.48160524046190
2017-01-01	8.69567492941364