Year	Percent of Total
1960-01-01	43.4034825268669
1961-01-01	43.6567149020315
1962-01-01	43.9986369935735
1963-01-01	44.3478685669979
1964-01-01	44.5830231702601
1965-01-01	44.6570639636930
1966-01-01	44.7608397455642
1967-01-01	44.7188557357569
1968-01-01	44.5723939635374
1969-01-01	44.3849965549942
1970-01-01	44.1890501269076
1971-01-01	44.1003963138729
1972-01-01	43.9582678393849
1973-01-01	43.7768265658547
1974-01-01	43.5600951192123
1975-01-01	43.3081245918541
1976-01-01	43.0963789587401
1977-01-01	42.8418734745873
1978-01-01	42.5496889246231
1979-01-01	42.2227905967242
1980-01-01	41.8647028845557
1981-01-01	41.5342957774189
1982-01-01	41.1779304987287
1983-01-01	40.7998616813226
1984-01-01	40.4067045862922
1985-01-01	40.0062502908751
1986-01-01	39.6635855038323
1987-01-01	39.3097358000928
1988-01-01	38.9498557167465
1989-01-01	38.5863539084471
1990-01-01	38.2189197571249
1991-01-01	37.9022061965455
1992-01-01	37.5617605143145
1993-01-01	37.2073860020115
1994-01-01	36.8496113822926
1995-01-01	36.4912172745043
1996-01-01	36.1577574624818
1997-01-01	35.8321384339597
1998-01-01	35.4994724136244
1999-01-01	35.1381286943920
2000-01-01	34.7386677030447
2001-01-01	34.3749336231804
2002-01-01	33.9673089015809
2003-01-01	33.5321052904448
2004-01-01	33.0995325044392
2005-01-01	32.6876799250512
2006-01-01	32.2500980849803
2007-01-01	31.8564286545456
2008-01-01	31.4879285515438
2009-01-01	31.1166185371930
2010-01-01	30.7313978395266
2011-01-01	30.4045204187423
2012-01-01	30.0495030177696
2013-01-01	29.6850815567581
2014-01-01	29.3382578202304
2015-01-01	29.0192716122427
2016-01-01	28.7165363000019
2017-01-01	28.4371030417222