Year	Percent of Total
1960-01-01	55.4889310960072
1961-01-01	54.9322907813474
1962-01-01	54.3823973873975
1963-01-01	53.8708003114208
1964-01-01	53.4554092455080
1965-01-01	53.1645325516816
1966-01-01	52.7931983468730
1967-01-01	52.5588590855825
1968-01-01	52.4302391476822
1969-01-01	52.3772328858316
1970-01-01	52.3790066679997
1971-01-01	52.2451032201974
1972-01-01	52.1963759483353
1973-01-01	52.2091823363690
1974-01-01	52.2398682148226
1975-01-01	52.2484356173967
1976-01-01	52.1528239952172
1977-01-01	52.0909749909388
1978-01-01	52.0423257533998
1979-01-01	52.0042226010012
1980-01-01	51.9931520422052
1981-01-01	51.8088449210657
1982-01-01	51.6406379035070
1983-01-01	51.4965962106065
1984-01-01	51.3868224369402
1985-01-01	51.3121346777848
1986-01-01	51.1056430446194
1987-01-01	50.9796789626554
1988-01-01	50.9138758077446
1989-01-01	50.8915702446251
1990-01-01	50.9081765040307
1991-01-01	50.8931941718255
1992-01-01	50.9403182051470
1993-01-01	51.0456870417607
1994-01-01	51.2145315471027
1995-01-01	51.4463792138731
1996-01-01	51.6694738522431
1997-01-01	51.9381296655265
1998-01-01	52.2500654850258
1999-01-01	52.6024490969050
2000-01-01	52.9876077933907
2001-01-01	53.2968871427338
2002-01-01	53.6437691293270
2003-01-01	54.0106410887312
2004-01-01	54.3780599703966
2005-01-01	54.7313967499800
2006-01-01	54.9912599273656
2007-01-01	55.2484336523176
2008-01-01	55.5005941612437
2009-01-01	55.7526750756032
2010-01-01	56.0058692865801
2011-01-01	56.1824818241389
2012-01-01	56.3711892223444
2013-01-01	56.5656102494943
2014-01-01	56.7634335679530
2015-01-01	56.9647965588919
2016-01-01	57.0987215953725
2017-01-01	57.2636845260913