Year	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