Year	Percent of Total
1960-01-01	35.0605470979053
1961-01-01	35.0290391018935
1962-01-01	35.5125401287072
1963-01-01	36.2383659252379
1964-01-01	36.8200108229639
1965-01-01	37.0894095812930
1966-01-01	37.7015275392303
1967-01-01	37.7674789975151
1968-01-01	37.5564387310751
1969-01-01	37.4477837881267
1970-01-01	37.5911045661662
1971-01-01	37.4374588569217
1972-01-01	37.6131762933088
1973-01-01	37.8836780785462
1974-01-01	37.8793742343973
1975-01-01	37.4268020082128
1976-01-01	36.8157609942132
1977-01-01	35.7287943138745
1978-01-01	34.3279521617498
1979-01-01	32.9212389118048
1980-01-01	31.6860184620978
1981-01-01	30.2795579172565
1982-01-01	29.1979455596893
1983-01-01	28.3214870911060
1984-01-01	27.4444724744059
1985-01-01	26.4919360717343
1986-01-01	25.8200878887051
1987-01-01	25.0387479822664
1988-01-01	24.2547459677435
1989-01-01	23.6159526492563
1990-01-01	23.1707166104663
1991-01-01	22.9278333693594
1992-01-01	22.7441110488856
1993-01-01	22.6330873201048
1994-01-01	22.5785522163091
1995-01-01	22.5557335506563
1996-01-01	22.3357752003191
1997-01-01	22.2554638045110
1998-01-01	22.2121335342595
1999-01-01	22.0790919607230
2000-01-01	21.8039957183095
2001-01-01	21.4877305247681
2002-01-01	21.0075897677999
2003-01-01	20.4314406061067
2004-01-01	19.8780662825873
2005-01-01	19.4066545654373
2006-01-01	18.8740529696935
2007-01-01	18.4295708117183
2008-01-01	18.0562017529294
2009-01-01	17.7115247978505
2010-01-01	17.3793270673537
2011-01-01	17.0987201632177
2012-01-01	16.8578315547876
2013-01-01	16.6494058490381
2014-01-01	16.4626342477080
2015-01-01	16.2881304884067
2016-01-01	16.1761494571881
2017-01-01	16.0339169652395