Year	Percent of Total
1960-01-01	38.2234325460076
1961-01-01	38.4813243669676
1962-01-01	38.6759795014940
1963-01-01	38.8061024605896
1964-01-01	38.8664865551862
1965-01-01	38.8635395388503
1966-01-01	38.9271633205595
1967-01-01	38.9080537723751
1968-01-01	38.8335859070297
1969-01-01	38.7445110698137
1970-01-01	38.6561085075421
1971-01-01	38.6125133331957
1972-01-01	38.5677210511407
1973-01-01	38.5205038160026
1974-01-01	38.4529813347772
1975-01-01	38.3565036997614
1976-01-01	38.3884055314798
1977-01-01	38.3739404878273
1978-01-01	38.3469470645738
1979-01-01	38.3437218505418
1980-01-01	38.3703478206618
1981-01-01	38.4096771787871
1982-01-01	38.4552052893082
1983-01-01	38.5070101505601
1984-01-01	38.5460994491122
1985-01-01	38.5536260828442
1986-01-01	38.5967514071131
1987-01-01	38.5688307610258
1988-01-01	38.4995605355373
1989-01-01	38.4088943421417
1990-01-01	38.2931966770229
1991-01-01	38.2150487624796
1992-01-01	38.1357861554125
1993-01-01	38.0329969816084
1994-01-01	37.8714268062417
1995-01-01	37.6565274338284
1996-01-01	37.5345434818454
1997-01-01	37.3327036095563
1998-01-01	37.0811975310981
1999-01-01	36.7877209975595
2000-01-01	36.4787448216185
2001-01-01	36.1129114203713
2002-01-01	35.7310800109599
2003-01-01	35.3390658132408
2004-01-01	34.9324390463282
2005-01-01	34.5079313844450
2006-01-01	33.8898647301681
2007-01-01	33.2787375394282
2008-01-01	32.7027196309311
2009-01-01	32.1868698745920
2010-01-01	31.7394270074796
2011-01-01	31.4851353639794
2012-01-01	31.2413967351106
2013-01-01	31.0323242816538
2014-01-01	30.8550311223145
2015-01-01	30.6886331817077
2016-01-01	30.5585320129831
2017-01-01	30.4127477006186