Year	Percent of Total
1960-01-01	52.8139983194108
1961-01-01	52.0412126862048
1962-01-01	50.8088036534877
1963-01-01	49.4504582588010
1964-01-01	48.4502738489855
1965-01-01	47.9777727846242
1966-01-01	47.3045001459732
1967-01-01	47.1611717930266
1968-01-01	47.3039777250504
1969-01-01	47.4332695378413
1970-01-01	47.4729642706460
1971-01-01	47.4651271832142
1972-01-01	47.2397323598306
1973-01-01	46.9485906851523
1974-01-01	46.7821309476591
1975-01-01	46.8121267293878
1976-01-01	46.6567026734685
1977-01-01	46.7575888340519
1978-01-01	47.0554891852235
1979-01-01	47.4167448612857
1980-01-01	47.7448658152426
1981-01-01	48.4574865741662
1982-01-01	49.0569655381200
1983-01-01	49.5352179531130
1984-01-01	49.9086933616034
1985-01-01	50.1918627348295
1986-01-01	50.1641248910779
1987-01-01	50.0841815613140
1988-01-01	49.9740650527344
1989-01-01	49.8359110220058
1990-01-01	49.6596788959966
1991-01-01	49.6416467105226
1992-01-01	49.6549611518004
1993-01-01	49.7157289425333
1994-01-01	49.8433362520968
1995-01-01	50.0546094205748
1996-01-01	50.2744669272995
1997-01-01	50.5542965639738
1998-01-01	50.9061326598343
1999-01-01	51.3487455575495
2000-01-01	51.8887374476819
2001-01-01	52.6219473717423
2002-01-01	53.4250817286212
2003-01-01	54.2969963946304
2004-01-01	55.2189178555544
2005-01-01	56.1688865850344
2006-01-01	57.0763007102819
2007-01-01	57.9701832504862
2008-01-01	58.8512231479918
2009-01-01	59.7173230200236
2010-01-01	60.5614430395872
2011-01-01	61.3749761350373
2012-01-01	62.2072108004412
2013-01-01	63.0133088255087
2014-01-01	63.7402006317945
2015-01-01	64.3621003803623
2016-01-01	64.9026984950701
2017-01-01	65.3345241842793