Year	Percent of Total
1960-01-01	2.66489063852171
1961-01-01	2.88889255000165
1962-01-01	3.13039723661485
1963-01-01	3.35852746263561
1964-01-01	3.51252428793059
1965-01-01	3.59379452965721
1966-01-01	3.63479074780537
1967-01-01	3.62364208020585
1968-01-01	3.58255347816517
1969-01-01	3.54156577885392
1970-01-01	3.50552124274752
1971-01-01	3.45161600847111
1972-01-01	3.39343445462868
1973-01-01	3.33483877802497
1974-01-01	3.27640984908658
1975-01-01	3.22003670293882
1976-01-01	3.19976076555024
1977-01-01	3.18558024786353
1978-01-01	3.17487589796932
1979-01-01	3.16065267814282
1980-01-01	3.14561136478945
1981-01-01	3.10006331794414
1982-01-01	3.04187137160082
1983-01-01	2.98394318842401
1984-01-01	2.92985775135226
1985-01-01	2.88551371671449
1986-01-01	2.87155983043918
1987-01-01	2.85746157573476
1988-01-01	2.84068564299372
1989-01-01	2.81415187978355
1990-01-01	2.77706516162135
1991-01-01	2.75944418290710
1992-01-01	2.72857043275860
1993-01-01	2.69872973227753
1994-01-01	2.67850239816737
1995-01-01	2.67214141554736
1996-01-01	2.70198582289718
1997-01-01	2.74117179501352
1998-01-01	2.78131183715054
1999-01-01	2.80994575855834
2000-01-01	2.82398105712672
2001-01-01	2.86915510802094
2002-01-01	2.89802463803410
2003-01-01	2.91985343656341
2004-01-01	2.94966006580498
2005-01-01	2.99051895676602
2006-01-01	3.05428501397942
2007-01-01	3.12289528137299
2008-01-01	3.19439736598497
2009-01-01	3.25783455633730
2010-01-01	3.31040754845677
2011-01-01	3.34479831879825
2012-01-01	3.37515026353913
2013-01-01	3.40222852001640
2014-01-01	3.42447663265590
2015-01-01	3.44402041254030
2016-01-01	3.47803456346896
2017-01-01	3.50719645109210