Annual Percent of Total
1960-01-01 27.3526473357393
1961-01-01 27.4422604564494
1962-01-01 27.2594453598635
1963-01-01 26.9190305400290
1964-01-01 26.6317443052934
1965-01-01 26.5016619127096
1966-01-01 26.2081054596822
1967-01-01 26.1258681538215
1968-01-01 26.1652889763959
1969-01-01 26.1717592252782
1970-01-01 26.0704670260670
1971-01-01 25.9990980964188
1972-01-01 25.7643939547705
1973-01-01 25.4324465070668
1974-01-01 25.1227595237070
1975-01-01 24.8964335631505
1976-01-01 24.5612950703882
1977-01-01 24.3382443508532
1978-01-01 24.1629120092571
1979-01-01 23.9384322417323
1980-01-01 23.6244647363269
1981-01-01 23.4612227896268
1982-01-01 23.1786467099802
1983-01-01 22.8243868727793
1984-01-01 22.4632653026259
1985-01-01 22.1150147387315
1986-01-01 21.7198719712544
1987-01-01 21.2932873049530
1988-01-01 20.8235528926725
1989-01-01 20.3068476649051
1990-01-01 19.7626841762878
1991-01-01 19.2186207320672
1992-01-01 18.7134816264627
1993-01-01 18.2217438191038
1994-01-01 17.7119909763554
1995-01-01 17.1782517523026
1996-01-01 16.8502143937935
1997-01-01 16.4689968354520
1998-01-01 16.0759186005431
1999-01-01 15.7277922819885
2000-01-01 15.4498439659458
2001-01-01 15.2938316393962
2002-01-01 15.1897881026485
2003-01-01 15.1314969706678
2004-01-01 15.0975965877573
2005-01-01 15.0735355277190
2006-01-01 15.0171314878069
2007-01-01 15.0089663407023
2008-01-01 15.0162872810342
2009-01-01 14.9943445497433
2010-01-01 14.9182444005572
2011-01-01 14.9521330356248
2012-01-01 14.8835889363371
2013-01-01 14.7539328522343
2014-01-01 14.6310438442977
2015-01-01 14.5459626664765
2016-01-01 14.3466983603661
2017-01-01 14.2145364426319