Year	Percent of Total
1960-01-01	50.0392606751437
1961-01-01	49.5816886541745
1962-01-01	49.2182719348161
1963-01-01	48.9558687708308
1964-01-01	48.8107612350963
1965-01-01	48.8068136493891
1966-01-01	48.8721951601229
1967-01-01	48.9680723096567
1968-01-01	49.0879492119753
1969-01-01	49.2351364364817
1970-01-01	49.4163992657469
1971-01-01	50.0486209582953
1972-01-01	50.6517089873509
1973-01-01	51.1728746869503
1974-01-01	51.5849491832318
1975-01-01	51.9148183057783
1976-01-01	52.3104995219473
1977-01-01	52.6401320000420
1978-01-01	52.9688037656225
1979-01-01	53.3620438670847
1980-01-01	53.8578971047987
1981-01-01	54.5258477329827
1982-01-01	55.1123461752124
1983-01-01	55.5816306094887
1984-01-01	56.0182348471851
1985-01-01	56.5553226424033
1986-01-01	57.2870487495078
1987-01-01	58.1429057987660
1988-01-01	58.9674597159302
1989-01-01	59.5788993717018
1990-01-01	59.9142483139583
1991-01-01	60.1291971263850
1992-01-01	60.1798608270711
1993-01-01	60.1094382893333
1994-01-01	60.0396654807462
1995-01-01	60.0436626730120
1996-01-01	60.1046647616822
1997-01-01	60.2082812849272
1998-01-01	60.2449759351516
1999-01-01	60.1079337674340
2000-01-01	59.8045137335541
2001-01-01	59.7554312786885
2002-01-01	59.6010820818105
2003-01-01	59.4504008076004
2004-01-01	59.4451953829698
2005-01-01	59.6438359083077
2006-01-01	60.2291085524165
2007-01-01	60.9094640906362
2008-01-01	61.6347810707021
2009-01-01	62.2812605187389
2010-01-01	62.7686335653320
2011-01-01	63.3991456414364
2012-01-01	63.9140555391048
2013-01-01	64.3451029639313
2014-01-01	64.7467294041208
2015-01-01	65.1419492683282
2016-01-01	65.4112294921913
2017-01-01	65.6969964993656