Year	Percent of Total
1960-01-01	63.1690349088758
1961-01-01	61.1392542330870
1962-01-01	59.5263223243109
1963-01-01	58.2202346635087
1964-01-01	57.1450819161527
1965-01-01	56.2704487931354
1966-01-01	54.0045108457079
1967-01-01	52.0133189928249
1968-01-01	50.3383490848871
1969-01-01	48.9971069060506
1970-01-01	47.9913269497528
1971-01-01	47.8496604727062
1972-01-01	47.9138991707185
1973-01-01	48.1245729037483
1974-01-01	48.3587455063840
1975-01-01	48.5297856113889
1976-01-01	48.3112446250810
1977-01-01	48.0030651691562
1978-01-01	47.7494477683180
1979-01-01	47.7177303586655
1980-01-01	47.9478456855786
1981-01-01	47.5461578133058
1982-01-01	47.5513140032014
1983-01-01	47.7391893777787
1984-01-01	47.8231859883236
1985-01-01	47.7073161317714
1986-01-01	47.8772019644652
1987-01-01	47.6879393008425
1988-01-01	47.3828446149630
1989-01-01	47.2681340535892
1990-01-01	47.4594575610441
1991-01-01	47.6086470497188
1992-01-01	48.0793832480474
1993-01-01	48.6990041760360
1994-01-01	49.2147483726295
1995-01-01	49.5429167918769
1996-01-01	49.8870525768314
1997-01-01	50.0141106119429
1998-01-01	50.0397247747680
1999-01-01	50.1155380245206
2000-01-01	50.3145606972281
2001-01-01	50.4271935151318
2002-01-01	50.6988108137954
2003-01-01	51.0278219610169
2004-01-01	51.3091485763544
2005-01-01	51.5099916468547
2006-01-01	51.6726501305483
2007-01-01	51.8188116565809
2008-01-01	51.9510163977641
2009-01-01	52.0832723504651
2010-01-01	52.2291390122213
2011-01-01	52.4837807606264
2012-01-01	52.7095670051233
2013-01-01	52.9407361864792
2014-01-01	53.2138487760501
2015-01-01	53.5481429586864
2016-01-01	53.8812465609524
2017-01-01	54.2742760379196