Year	Percent of Total
1960-01-01	38.9201649028562
1961-01-01	39.1153372568483
1962-01-01	39.2122260859335
1963-01-01	39.2438920053002
1964-01-01	39.2385607119568
1965-01-01	39.2104214056234
1966-01-01	39.5459060785178
1967-01-01	39.7767560109950
1968-01-01	39.9395278690949
1969-01-01	40.0729506608623
1970-01-01	40.2023356593849
1971-01-01	40.6324398285514
1972-01-01	41.0079660196409
1973-01-01	41.3394516748908
1974-01-01	41.6199254782631
1975-01-01	41.8456208607170
1976-01-01	42.3182703244839
1977-01-01	42.6669962996044
1978-01-01	42.9300122800780
1979-01-01	43.1494145632359
1980-01-01	43.3440966577634
1981-01-01	43.7083288223269
1982-01-01	44.0135712298097
1983-01-01	44.2567248336059
1984-01-01	44.4316438016611
1985-01-01	44.5445908068061
1986-01-01	44.8179370510152
1987-01-01	44.9896992763717
1988-01-01	45.0762391571940
1989-01-01	45.0683709113706
1990-01-01	44.9287679784502
1991-01-01	45.0277699707118
1992-01-01	45.0630660498895
1993-01-01	45.0180960272319
1994-01-01	44.9130536991951
1995-01-01	44.7998850945502
1996-01-01	44.8156736371385
1997-01-01	44.7407765265227
1998-01-01	44.6279279482071
1999-01-01	44.5459160760403
2000-01-01	44.5600932629932
2001-01-01	44.6225660440581
2002-01-01	44.6242810480722
2003-01-01	44.5980603317711
2004-01-01	44.5334527027710
2005-01-01	44.3949229982650
2006-01-01	44.4208893202104
2007-01-01	44.4062647693418
2008-01-01	44.3276577633921
2009-01-01	44.1743129443161
2010-01-01	43.9534768499022
2011-01-01	43.8367818706619
2012-01-01	43.6316148305753
2013-01-01	43.3622326471570
2014-01-01	43.0578788845346
2015-01-01	42.7333054673709
2016-01-01	42.4149595940613
2017-01-01	42.0912103564119