Year	Percent of Total
1960-01-01	27.3708477239283
1961-01-01	27.5156347499170
1962-01-01	27.5661040443509
1963-01-01	27.5779115119930
1964-01-01	27.6210613483210
1965-01-01	27.7166950037376
1966-01-01	27.7824967339981
1967-01-01	27.8870426582320
1968-01-01	28.0017521027698
1969-01-01	28.0838832547941
1970-01-01	28.1141860060230
1971-01-01	28.0166489751445
1972-01-01	27.9149979393290
1973-01-01	27.7885176111387
1974-01-01	27.6234074906678
1975-01-01	27.4157111666313
1976-01-01	27.2352067874336
1977-01-01	26.9841913163451
1978-01-01	26.6736010389872
1979-01-01	26.3164627299492
1980-01-01	25.9155730003033
1981-01-01	25.5127161269306
1982-01-01	25.0393692607078
1983-01-01	24.5140703287560
1984-01-01	23.9605232820825
1985-01-01	23.3893427017137
1986-01-01	22.6950259399374
1987-01-01	22.0458382424778
1988-01-01	21.4032127706567
1989-01-01	20.7218165231833
1990-01-01	19.9943255629876
1991-01-01	19.3288336987859
1992-01-01	18.6280799962324
1993-01-01	17.9244466919711
1994-01-01	17.2672340764121
1995-01-01	16.6807293305789
1996-01-01	16.1948174880435
1997-01-01	15.7419297929111
1998-01-01	15.3400414894610
1999-01-01	15.0056501372740
2000-01-01	14.7505784988555
2001-01-01	14.5335089642582
2002-01-01	14.4070884438254
2003-01-01	14.3477311049908
2004-01-01	14.3176105703707
2005-01-01	14.2976945610335
2006-01-01	14.3675809155272
2007-01-01	14.4280686607426
2008-01-01	14.4906280964792
2009-01-01	14.5578739958919
2010-01-01	14.6129882409466
2011-01-01	14.7475466294009
2012-01-01	14.8337219023060
2013-01-01	14.8784584065893
2014-01-01	14.8995868111543
2015-01-01	14.9079121741991
2016-01-01	14.7778623848635
2017-01-01	14.6874808068055