Year	Percent of Total
1960-01-01	42.3197125505185
1961-01-01	42.4749117685261
1962-01-01	42.6775560909482
1963-01-01	42.8765560338274
1964-01-01	42.9780370481829
1965-01-01	42.9429149091409
1966-01-01	43.0380661300157
1967-01-01	42.9882762486356
1968-01-01	42.8431447823159
1969-01-01	42.6729940932438
1970-01-01	42.5133905842676
1971-01-01	42.5201892539459
1972-01-01	42.4972270604840
1973-01-01	42.4579593369524
1974-01-01	42.4056254294018
1975-01-01	42.3402712218598
1976-01-01	42.3851324838134
1977-01-01	42.4093042042908
1978-01-01	42.4133351226337
1979-01-01	42.3906172890974
1980-01-01	42.3345245389855
1981-01-01	42.3728976771654
1982-01-01	42.3524236262040
1983-01-01	42.2878173679018
1984-01-01	42.1929617569381
1985-01-01	42.0702723152836
1986-01-01	41.9867769935529
1987-01-01	41.8653859123626
1988-01-01	41.7086127611889
1989-01-01	41.5163454184309
1990-01-01	41.2889914652979
1991-01-01	41.0695227086197
1992-01-01	40.8150811579893
1993-01-01	40.5312885586332
1994-01-01	40.2249213187847
1995-01-01	39.9014816735508
1996-01-01	39.6240179551699
1997-01-01	39.3193242665505
1998-01-01	38.9962615187608
1999-01-01	38.6613631275303
2000-01-01	38.3160789264408
2001-01-01	38.0184255049948
2002-01-01	37.6926957147785
2003-01-01	37.3480605918901
2004-01-01	36.9924934272745
2005-01-01	36.6278377221229
2006-01-01	36.2647945231745
2007-01-01	35.8952295856439
2008-01-01	35.5141614118130
2009-01-01	35.1123525271889
2010-01-01	34.6859151047131
2011-01-01	34.2672103936133
2012-01-01	33.8197641098685
2013-01-01	33.3554609767598
2014-01-01	32.8933790903924
2015-01-01	32.4452374214489
2016-01-01	32.0322630241584
2017-01-01	31.6396630352166