Year	Percent of Total
1960-01-01	52.0459713495278
1961-01-01	51.7063781811875
1962-01-01	51.4566399369865
1963-01-01	51.2780257664544
1964-01-01	51.1322486266861
1965-01-01	51.0001379148299
1966-01-01	50.7596283990099
1967-01-01	50.5498940080515
1968-01-01	50.3700194248354
1969-01-01	50.2170263014659
1970-01-01	50.0844683653072
1971-01-01	49.8721121662433
1972-01-01	49.6829934565784
1973-01-01	49.5187653757699
1974-01-01	49.3798752572222
1975-01-01	49.2644442037507
1976-01-01	49.0154046968009
1977-01-01	48.8246158096990
1978-01-01	48.6807538951898
1979-01-01	48.5678506997595
1980-01-01	48.4831911325020
1981-01-01	48.4332245250098
1982-01-01	48.3970733859273
1983-01-01	48.3869546724997
1984-01-01	48.3970022471381
1985-01-01	48.4059368728593
1986-01-01	48.5237176248190
1987-01-01	48.6715264110018
1988-01-01	48.8496556962531
1989-01-01	49.0877669986862
1990-01-01	49.4164548923637
1991-01-01	49.3232447666784
1992-01-01	49.3410843301686
1993-01-01	49.4678174291821
1994-01-01	49.6808151424864
1995-01-01	49.9659655783978
1996-01-01	50.3548714354977
1997-01-01	50.7985597537836
1998-01-01	51.3124153881691
1999-01-01	51.9141110279076
2000-01-01	52.6027162382662
2001-01-01	53.0565453194859
2002-01-01	53.5243725310612
2003-01-01	53.9914768547129
2004-01-01	54.4321599045891
2005-01-01	54.8343254605185
2006-01-01	55.3992185729049
2007-01-01	55.9537048261032
2008-01-01	56.4894032860556
2009-01-01	57.0015457259618
2010-01-01	57.4840606795733
2011-01-01	57.8718931033301
2012-01-01	58.2592107729951
2013-01-01	58.6264094077971
2014-01-01	58.9554295933046
2015-01-01	59.2440093372989
2016-01-01	59.4670679280291
2017-01-01	59.6508037277638