Year	Percent of Total
1960-01-01	41.2930116298399
1961-01-01	42.5327885451535
1962-01-01	43.6012798595389
1963-01-01	44.6991130571461
1964-01-01	45.8638394199697
1965-01-01	46.9255352636437
1966-01-01	46.4073417457503
1967-01-01	45.9377853037034
1968-01-01	45.5472881043393
1969-01-01	45.1847429905408
1970-01-01	44.8028033207121
1971-01-01	43.9494898144450
1972-01-01	42.7815234230106
1973-01-01	41.5168227381464
1974-01-01	40.3920432216140
1975-01-01	39.5174512180024
1976-01-01	38.1910964504215
1977-01-01	37.1003545806877
1978-01-01	36.2027124365867
1979-01-01	35.3835203239225
1980-01-01	34.5729782599031
1981-01-01	34.1478669945472
1982-01-01	33.8694131364166
1983-01-01	33.7032795734184
1984-01-01	33.6119658077682
1985-01-01	33.5541091481296
1986-01-01	33.5584868575858
1987-01-01	33.4182679136607
1988-01-01	33.2356696660805
1989-01-01	33.0150283730695
1990-01-01	32.6902331171070
1991-01-01	32.4369072023383
1992-01-01	31.9807221360883
1993-01-01	31.4024464158832
1994-01-01	30.7937946243368
1995-01-01	30.2464613206694
1996-01-01	30.0968776569639
1997-01-01	29.9001563209117
1998-01-01	29.8367937533200
1999-01-01	29.9422664540606
2000-01-01	30.1411044606343
2001-01-01	29.0664885190861
2002-01-01	28.0494539874964
2003-01-01	27.1528204943811
2004-01-01	26.3750710973576
2005-01-01	25.6842351501629
2006-01-01	24.1907985484352
2007-01-01	22.9368727018576
2008-01-01	21.9127212697046
2009-01-01	21.0565311059898
2010-01-01	20.3115253751022
2011-01-01	20.3517413001489
2012-01-01	20.3927498256060
2013-01-01	20.4970157616137
2014-01-01	20.6677357102717
2015-01-01	20.8496524778493
2016-01-01	20.2915299286893
2017-01-01	19.7218381009042