Annual 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