Annual Percent of Total
1960-01-01 38.6548353360511
1961-01-01 39.7829297174182
1962-01-01 40.6608822179957
1963-01-01 41.2938642407615
1964-01-01 41.7009246628668
1965-01-01 41.8780490893206
1966-01-01 41.7885784508208
1967-01-01 41.4332459501933
1968-01-01 40.8550938304305
1969-01-01 40.1352456936366
1970-01-01 39.3376804161477
1971-01-01 38.2249374542549
1972-01-01 37.2224091901705
1973-01-01 36.2775321708608
1974-01-01 35.3030034822931
1975-01-01 34.2705357360338
1976-01-01 33.4165980580562
1977-01-01 32.4739104578589
1978-01-01 31.5542980258630
1979-01-01 30.8023501978449
1980-01-01 30.2702055745768
1981-01-01 29.9319397273015
1982-01-01 29.8052469779434
1983-01-01 29.8192363723270
1984-01-01 29.8641798517468
1985-01-01 29.8846650189527
1986-01-01 29.9240092728851
1987-01-01 29.9680585595007
1988-01-01 30.0237027880950
1989-01-01 30.0691735174266
1990-01-01 30.0438786772239
1991-01-01 30.0268368798697
1992-01-01 29.9338621649176
1993-01-01 29.7622906022959
1994-01-01 29.5301279669637
1995-01-01 29.2573497004670
1996-01-01 28.7169904820222
1997-01-01 28.0994521056875
1998-01-01 27.4021740389181
1999-01-01 26.6314170495015
2000-01-01 25.8111186256918
2001-01-01 24.8087377956537
2002-01-01 23.8759259131078
2003-01-01 23.0107568213464
2004-01-01 22.2058700025195
2005-01-01 21.4615368876035
2006-01-01 20.9301673145175
2007-01-01 20.4171689868860
2008-01-01 19.9634828176685
2009-01-01 19.6332528325297
2010-01-01 19.4607395585670
2011-01-01 19.4278651862006
2012-01-01 19.4611096344731
2013-01-01 19.5633053154492
2014-01-01 19.7027066085843
2015-01-01 19.8445636709577
2016-01-01 19.9201932702775
2017-01-01 20.0066542681158