Year	Percent of Total
1960-01-01	42.9364949042180
1961-01-01	43.3386435794082
1962-01-01	43.7109561008004
1963-01-01	44.0276615476973
1964-01-01	44.2422553696232
1965-01-01	44.3403863163535
1966-01-01	44.5208244088931
1967-01-01	44.5587878181291
1968-01-01	44.5067451341281
1969-01-01	44.4114619949819
1970-01-01	44.2961723247235
1971-01-01	44.2870491485668
1972-01-01	44.2293454124264
1973-01-01	44.1350867762441
1974-01-01	44.0268223606018
1975-01-01	43.9150507540205
1976-01-01	43.8488679638118
1977-01-01	43.7819314443323
1978-01-01	43.7129436049352
1979-01-01	43.6403264745314
1980-01-01	43.5712347591184
1981-01-01	43.5823338937602
1982-01-01	43.5714304810392
1983-01-01	43.5447470891638
1984-01-01	43.5026075444564
1985-01-01	43.4338292241514
1986-01-01	43.4566068162155
1987-01-01	43.4152244921994
1988-01-01	43.3086639734797
1989-01-01	43.1251171467741
1990-01-01	42.8908872210213
1991-01-01	42.5716693570945
1992-01-01	42.2428240184574
1993-01-01	41.7603497534361
1994-01-01	41.2027882773461
1995-01-01	40.5252506475937
1996-01-01	39.7922380549261
1997-01-01	39.0327000039009
1998-01-01	38.2556873323222
1999-01-01	37.4634159009687
2000-01-01	36.6543690506964
2001-01-01	35.7804295766762
2002-01-01	34.8993659352467
2003-01-01	34.0234015277566
2004-01-01	33.1819227677089
2005-01-01	32.4083688779457
2006-01-01	31.8093697453244
2007-01-01	31.2675719425871
2008-01-01	30.8086300855293
2009-01-01	30.4494114153235
2010-01-01	30.1906135668682
2011-01-01	30.0701218422905
2012-01-01	30.0380669853798
2013-01-01	30.0642746644758
2014-01-01	30.0958330438023
2015-01-01	30.0948229155560
2016-01-01	30.1013781418397
2017-01-01	30.0207759206345