Annual Percent of Total
1960-01-01 47.0007964442617
1961-01-01 47.1003695726687
1962-01-01 47.3111987148997
1963-01-01 47.5258808087227
1964-01-01 47.5964289943329
1965-01-01 47.4680785521532
1966-01-01 47.3795689993615
1967-01-01 47.1190207672747
1968-01-01 46.7457921317493
1969-01-01 46.3556427079681
1970-01-01 45.9972061232470
1971-01-01 45.6783883120849
1972-01-01 45.3732010736868
1973-01-01 45.0782248651043
1974-01-01 44.7777894479150
1975-01-01 44.4652787578504
1976-01-01 44.1956140987372
1977-01-01 43.9287210019681
1978-01-01 43.6609276638601
1979-01-01 43.3887456508594
1980-01-01 43.1114834180954
1981-01-01 42.8791176344526
1982-01-01 42.6226429463335
1983-01-01 42.3564824066870
1984-01-01 42.0999639633669
1985-01-01 41.8617707706228
1986-01-01 41.6709913212068
1987-01-01 41.5031440078553
1988-01-01 41.3413616283604
1989-01-01 41.1582423838627
1990-01-01 40.9391730538650
1991-01-01 40.7675708207626
1992-01-01 40.5438078480121
1993-01-01 40.2860547538556
1994-01-01 40.0219868536113
1995-01-01 39.7633359950564
1996-01-01 39.5016848153812
1997-01-01 39.2608070286794
1998-01-01 39.0219870632990
1999-01-01 38.7640364656106
2000-01-01 38.4827544628574
2001-01-01 38.2329599776264
2002-01-01 37.9694798140330
2003-01-01 37.6972460505988
2004-01-01 37.4084149088482
2005-01-01 37.0750088464996
2006-01-01 36.5542835444567
2007-01-01 35.9800048133408
2008-01-01 35.3254220761791
2009-01-01 34.6132929398775
2010-01-01 33.9014429880671
2011-01-01 33.5400114654032
2012-01-01 33.1735666030417
2013-01-01 32.8311049786724
2014-01-01 32.5199267001484
2015-01-01 32.2291805588519
2016-01-01 31.9649893899763
2017-01-01 31.7157536893781