Year	Percent of Total
1960-01-01	51.7783675769545
1961-01-01	51.5164389921358
1962-01-01	51.2655501959283
1963-01-01	51.0533385368881
1964-01-01	50.9288239661115
1965-01-01	50.9140322771801
1966-01-01	50.7722591493889
1967-01-01	50.7648282162047
1968-01-01	50.8537436072026
1969-01-01	50.9901595624830
1970-01-01	51.1521713353477
1971-01-01	51.2842196067849
1972-01-01	51.4232646828750
1973-01-01	51.5726230527423
1974-01-01	51.7468799591880
1975-01-01	51.9548164266641
1976-01-01	52.0911154746531
1977-01-01	52.2388407848195
1978-01-01	52.3905968874816
1979-01-01	52.5477438153642
1980-01-01	52.7218960229694
1981-01-01	52.9048426718083
1982-01-01	53.1111238075891
1983-01-01	53.3273884324385
1984-01-01	53.5412960128697
1985-01-01	53.7537216736463
1986-01-01	54.1942050650809
1987-01-01	54.6012694822065
1988-01-01	54.9849336837900
1989-01-01	55.3557954647785
1990-01-01	55.7103694321429
1991-01-01	56.1535124187647
1992-01-01	56.5520706045611
1993-01-01	56.8943551333577
1994-01-01	57.1741829720584
1995-01-01	57.3970414079911
1996-01-01	57.5167866288782
1997-01-01	57.6235191623943
1998-01-01	57.7138376653874
1999-01-01	57.7942133016502
2000-01-01	57.8815009681939
2001-01-01	58.0173560209158
2002-01-01	58.1811230841255
2003-01-01	58.3807178556267
2004-01-01	58.6186784207040
2005-01-01	58.8964665719350
2006-01-01	59.3731703475188
2007-01-01	59.8135440681518
2008-01-01	60.2489468194775
2009-01-01	60.7150957525782
2010-01-01	61.2214106743864
2011-01-01	61.7395875050060
2012-01-01	62.3178700858317
2013-01-01	62.8971086314549
2014-01-01	63.3915330361815
2015-01-01	63.7610776623697
2016-01-01	64.1158903416099
2017-01-01	64.3496173398791