Year	Percent of Total
1960-01-01	42.0998889326789
1961-01-01	42.2505001791034
1962-01-01	42.1885252187844
1963-01-01	42.0324946631337
1964-01-01	41.9371272617002
1965-01-01	41.9721453722334
1966-01-01	42.1496773996736
1967-01-01	42.3812550346978
1968-01-01	42.6395721159866
1969-01-01	42.8556587504415
1970-01-01	42.9908045899947
1971-01-01	43.2941734052257
1972-01-01	43.4784385857347
1973-01-01	43.5798874241575
1974-01-01	43.6344754132701
1975-01-01	43.6599596550680
1976-01-01	43.8441853066080
1977-01-01	43.9537774158640
1978-01-01	43.9984534905445
1979-01-01	43.9761946702232
1980-01-01	43.8869228588466
1981-01-01	44.0760740282602
1982-01-01	44.1533464795267
1983-01-01	44.1523875911797
1984-01-01	44.1234682182844
1985-01-01	44.1013917607421
1986-01-01	44.1321290728685
1987-01-01	44.1815852944526
1988-01-01	44.2077974299838
1989-01-01	44.1206811036912
1990-01-01	43.8527397260274
1991-01-01	44.1109357434802
1992-01-01	44.2413809322233
1993-01-01	44.2881802732467
1994-01-01	44.3534693893356
1995-01-01	44.5172342132199
1996-01-01	43.9799569405448
1997-01-01	43.4341867862938
1998-01-01	42.8576698545619
1999-01-01	42.1773746598917
2000-01-01	41.3581065055736
2001-01-01	40.1260176390773
2002-01-01	38.7964030283691
2003-01-01	37.4424558172958
2004-01-01	36.1445425609341
2005-01-01	34.9363957973864
2006-01-01	33.9539560982286
2007-01-01	33.0416124420998
2008-01-01	32.1934517440616
2009-01-01	31.3762320528289
2010-01-01	30.5719441317903
2011-01-01	29.9293729996894
2012-01-01	29.2514811406078
2013-01-01	28.5776660509490
2014-01-01	27.9596315529179
2015-01-01	27.4178103242882
2016-01-01	26.9365038576523
2017-01-01	26.5499436609254