Year	Percent of Total
1960-01-01	40.3125168003891
1961-01-01	40.5249820505453
1962-01-01	40.8550332793924
1963-01-01	41.2076949910384
1964-01-01	41.4278093513756
1965-01-01	41.4529632598369
1966-01-01	41.5692279055299
1967-01-01	41.4992330888537
1968-01-01	41.3096145536464
1969-01-01	41.1014929847647
1970-01-01	40.9262965300095
1971-01-01	40.9504982453114
1972-01-01	40.9439183181888
1973-01-01	40.9273607423824
1974-01-01	40.9077050066854
1975-01-01	40.8865454673163
1976-01-01	41.0350037552006
1977-01-01	41.1614317124626
1978-01-01	41.2678722735393
1979-01-01	41.3487318430795
1980-01-01	41.4006342569196
1981-01-01	41.6090224873615
1982-01-01	41.7552345591494
1983-01-01	41.8555916271138
1984-01-01	41.9267604896288
1985-01-01	41.9753615711498
1986-01-01	42.1507085845057
1987-01-01	42.2817024343283
1988-01-01	42.3719262532977
1989-01-01	42.4218769559528
1990-01-01	42.4318669082103
1991-01-01	42.3650149279914
1992-01-01	42.2317451622280
1993-01-01	42.0464958350095
1994-01-01	41.8236288363565
1995-01-01	41.5738565918428
1996-01-01	41.5013226954617
1997-01-01	41.4158936548035
1998-01-01	41.3131562603842
1999-01-01	41.1761540829368
2000-01-01	40.9875720438866
2001-01-01	40.7678955070234
2002-01-01	40.5276455078253
2003-01-01	40.2623333293121
2004-01-01	39.9730472204274
2005-01-01	39.6509953262224
2006-01-01	39.1159994723333
2007-01-01	38.6068055251286
2008-01-01	38.1116472934835
2009-01-01	37.5940177187156
2010-01-01	37.0206982261164
2011-01-01	36.1843956853601
2012-01-01	35.2740884468945
2013-01-01	34.3276168818569
2014-01-01	33.4092380176407
2015-01-01	32.5549280956964
2016-01-01	31.6794208531682
2017-01-01	30.8928258585788