Year	Percent of Total
1960-01-01	53.3661051188002
1961-01-01	52.9494410856163
1962-01-01	52.5703151756690
1963-01-01	52.2534520972402
1964-01-01	52.0432063874332
1965-01-01	51.9533905651587
1966-01-01	51.7600750996752
1967-01-01	51.7144823428645
1968-01-01	51.7647148806372
1969-01-01	51.8616579225186
1970-01-01	51.9807755274981
1971-01-01	51.9729521351938
1972-01-01	52.0184769339220
1973-01-01	52.1058562966364
1974-01-01	52.2170707891686
1975-01-01	52.3418827802760
1976-01-01	52.4109269762769
1977-01-01	52.4906138523007
1978-01-01	52.5795945681850
1979-01-01	52.6765163484236
1980-01-01	52.7730456931609
1981-01-01	52.7750279483393
1982-01-01	52.8021748628266
1983-01-01	52.8445225911979
1984-01-01	52.8974174228519
1985-01-01	52.9674382086028
1986-01-01	52.9273542287066
1987-01-01	52.9456211960223
1988-01-01	53.0233035323936
1989-01-01	53.1727346614346
1990-01-01	53.3787083282902
1991-01-01	53.6375541641647
1992-01-01	53.8888076678669
1993-01-01	54.3104730488625
1994-01-01	54.8048374083431
1995-01-01	55.4317982519171
1996-01-01	56.1010385702047
1997-01-01	56.8006962659763
1998-01-01	57.5209590884580
1999-01-01	58.2592395884141
2000-01-01	59.0167996563161
2001-01-01	59.8346176212115
2002-01-01	60.6630348016302
2003-01-01	61.4904918590223
2004-01-01	62.2902708653363
2005-01-01	63.0302206800003
2006-01-01	63.6214820587217
2007-01-01	64.1633342827203
2008-01-01	64.6249899269323
2009-01-01	64.9826437246574
2010-01-01	65.2321101661176
2011-01-01	65.3373577536976
2012-01-01	65.3511555739215
2013-01-01	65.2978597777368
2014-01-01	65.2214167771301
2015-01-01	65.1540683401414
2016-01-01	65.0444254182133
2017-01-01	64.9989627229521