Year	Percent of Total
1960-01-01	44.1018059653888
1961-01-01	44.2996956191001
1962-01-01	44.5164277177246
1963-01-01	44.7076019161293
1964-01-01	44.8085842396446
1965-01-01	44.7933061451477
1966-01-01	44.8468429764155
1967-01-01	44.7542474330272
1968-01-01	44.5644134026767
1969-01-01	44.3435517591183
1970-01-01	44.1210040850149
1971-01-01	43.9060319200013
1972-01-01	43.6922648502763
1973-01-01	43.4620310800187
1974-01-01	43.1845532086137
1975-01-01	42.8495983393863
1976-01-01	42.5447768035274
1977-01-01	42.1907035468803
1978-01-01	41.8036672799200
1979-01-01	41.4085914725855
1980-01-01	41.0188316103256
1981-01-01	40.6735424968984
1982-01-01	40.3287937739521
1983-01-01	39.9823060436485
1984-01-01	39.6238814292229
1985-01-01	39.2465933317680
1986-01-01	38.8914353299683
1987-01-01	38.5073896900052
1988-01-01	38.1041312090229
1989-01-01	37.6943700463724
1990-01-01	37.2829314422131
1991-01-01	36.8589184435546
1992-01-01	36.4375200095880
1993-01-01	36.0111472342567
1994-01-01	35.5703650180841
1995-01-01	35.1128503212620
1996-01-01	34.6622700364480
1997-01-01	34.2061043622831
1998-01-01	33.7440679567435
1999-01-01	33.2768090706535
2000-01-01	32.8041471381844
2001-01-01	32.3478891463328
2002-01-01	31.8753455284932
2003-01-01	31.3950069880262
2004-01-01	30.9179724858735
2005-01-01	30.4488590149883
2006-01-01	29.9516916454949
2007-01-01	29.4674359927151
2008-01-01	28.9903813137585
2009-01-01	28.5142224698730
2010-01-01	28.0391746162339
2011-01-01	27.5776092496360
2012-01-01	27.1311051832375
2013-01-01	26.6964951838585
2014-01-01	26.2705417482907
2015-01-01	25.8523865981503
2016-01-01	25.4873841811584
2017-01-01	25.1145096309816