Year	Percent of Total
1960-01-01	41.3557318926220
1961-01-01	41.0124268295055
1962-01-01	40.5666246023141
1963-01-01	40.0764781178606
1964-01-01	39.5252120117809
1965-01-01	38.9512854290875
1966-01-01	38.3197234607485
1967-01-01	37.6441277014891
1968-01-01	37.0274997049388
1969-01-01	36.5089121081746
1970-01-01	36.0721003707288
1971-01-01	35.7356980171490
1972-01-01	35.1663168216710
1973-01-01	34.4682616123340
1974-01-01	33.7551397491282
1975-01-01	33.1299836387633
1976-01-01	33.1674681884075
1977-01-01	33.1961215283678
1978-01-01	33.2781517285898
1979-01-01	33.4333432369115
1980-01-01	33.6757904144788
1981-01-01	32.1797021084532
1982-01-01	31.0772325484145
1983-01-01	30.2673202382068
1984-01-01	29.5836933124423
1985-01-01	28.9171366898332
1986-01-01	29.2022255058653
1987-01-01	29.1413810167613
1988-01-01	28.8960643902351
1989-01-01	28.6091324398640
1990-01-01	28.3132365750506
1991-01-01	27.9469774826612
1992-01-01	27.7249821903184
1993-01-01	27.6071344548873
1994-01-01	27.4814383892565
1995-01-01	27.2968419822575
1996-01-01	27.0306181840461
1997-01-01	26.6498069613623
1998-01-01	26.2509310902385
1999-01-01	25.9327031312835
2000-01-01	25.7296118135908
2001-01-01	24.5186306708209
2002-01-01	23.5353336668427
2003-01-01	22.7805967591557
2004-01-01	22.1935679411745
2005-01-01	21.7118780662371
2006-01-01	18.5955410923789
2007-01-01	16.2833411648803
2008-01-01	14.7172546428453
2009-01-01	13.7198104074731
2010-01-01	13.0841793674804
2011-01-01	13.2929724280168
2012-01-01	13.3599864996056
2013-01-01	13.4904528959023
2014-01-01	13.6817891029342
2015-01-01	13.8263392193312
2016-01-01	13.8818369027366
2017-01-01	13.8772913571518