Year	Percent of Total
1960-01-01	3.15049032127580
1961-01-01	3.19816491775723
1962-01-01	3.24434585822976
1963-01-01	3.28607093571223
1964-01-01	3.31968914995190
1965-01-01	3.34441583165685
1966-01-01	3.36851717272014
1967-01-01	3.38713383070168
1968-01-01	3.40362293547856
1969-01-01	3.42174588297516
1970-01-01	3.44400026129065
1971-01-01	3.48313740898156
1972-01-01	3.52053857701418
1973-01-01	3.55685985331982
1974-01-01	3.59259040744007
1975-01-01	3.62772680767312
1976-01-01	3.66629707351800
1977-01-01	3.69983779351478
1978-01-01	3.72796149747578
1979-01-01	3.74941485581028
1980-01-01	3.76438015588360
1981-01-01	3.78282403608623
1982-01-01	3.79483890823571
1983-01-01	3.80352919624835
1984-01-01	3.81288171678393
1985-01-01	3.82610059896910
1986-01-01	3.86476008311484
1987-01-01	3.90347196637489
1988-01-01	3.94441053971492
1989-01-01	3.99024879212723
1990-01-01	4.04253249928215
1991-01-01	4.13946683376084
1992-01-01	4.23702946420777
1993-01-01	4.33164947824158
1994-01-01	4.41784888766530
1995-01-01	4.49342590096705
1996-01-01	4.61181282728029
1997-01-01	4.71965935107503
1998-01-01	4.82493983686023
1999-01-01	4.93816877861638
2000-01-01	5.06524458003977
2001-01-01	5.22085627019015
2002-01-01	5.39116067513156
2003-01-01	5.56854139195829
2004-01-01	5.74190729685532
2005-01-01	5.90669370727955
2006-01-01	6.06976117526081
2007-01-01	6.22471933063450
2008-01-01	6.38033420719512
2009-01-01	6.54805088966527
2010-01-01	6.73438021327528
2011-01-01	6.95156084135843
2012-01-01	7.18018319644953
2013-01-01	7.42277582311806
2014-01-01	7.68207792003269
2015-01-01	7.96042299198064
2016-01-01	8.24733191136082
2017-01-01	8.55237960340999