Year	Percent of Total
1960-01-01	42.3900737710905
1961-01-01	42.4297181777114
1962-01-01	42.5683209038428
1963-01-01	42.7995884805981
1964-01-01	43.0604795883259
1965-01-01	43.2811629799934
1966-01-01	43.0557643168495
1967-01-01	42.7556697180376
1968-01-01	42.4587239246787
1969-01-01	42.2580488042472
1970-01-01	42.1554849604969
1971-01-01	41.4245699199945
1972-01-01	41.0770415938011
1973-01-01	40.9310808428105
1974-01-01	40.7311762894451
1975-01-01	40.3585307228852
1976-01-01	39.9441167017449
1977-01-01	39.1931449792249
1978-01-01	38.2818974458224
1979-01-01	37.4936903005358
1980-01-01	36.9579561475546
1981-01-01	36.1729094319300
1982-01-01	35.8011576438543
1983-01-01	35.6445976011049
1984-01-01	35.4155163793666
1985-01-01	34.9853208741856
1986-01-01	34.7286633686139
1987-01-01	34.1525845032519
1988-01-01	33.4240787788948
1989-01-01	32.8109303590644
1990-01-01	32.4343829973160
1991-01-01	31.9628058027850
1992-01-01	31.8125455597556
1993-01-01	31.8167905150001
1994-01-01	31.7098896319252
1995-01-01	31.3689095127610
1996-01-01	31.2051164593538
1997-01-01	30.7837056138272
1998-01-01	30.2130593670275
1999-01-01	29.6908424509149
2000-01-01	29.3061197086173
2001-01-01	28.4869777491877
2002-01-01	27.7693857813344
2003-01-01	27.0898126975480
2004-01-01	26.3733776501739
2005-01-01	25.5979517022071
2006-01-01	25.1630289134383
2007-01-01	24.6848052160501
2008-01-01	24.0808085443219
2009-01-01	23.3410172013436
2010-01-01	22.5351410074495
2011-01-01	22.1917897907073
2012-01-01	21.7251417190133
2013-01-01	21.2588802884106
2014-01-01	20.9033176421949
2015-01-01	20.6791990445613
2016-01-01	20.4962784230329
2017-01-01	20.4539648574341