Year	Percent of Total
1960-01-01	56.3482235890673
1961-01-01	55.9827809536263
1962-01-01	55.7180314358371
1963-01-01	55.5262011117739
1964-01-01	55.3755032958154
1965-01-01	55.2480352163436
1966-01-01	54.8692318243622
1967-01-01	54.5416926273330
1968-01-01	54.2683980485241
1969-01-01	54.0639639779790
1970-01-01	53.9341464281905
1971-01-01	53.5366944818107
1972-01-01	53.2612851154807
1973-01-01	53.0730970816374
1974-01-01	52.9240281647095
1975-01-01	52.7876065574303
1976-01-01	52.3908928174953
1977-01-01	52.0254698633444
1978-01-01	51.7019228369367
1979-01-01	51.4394776948931
1980-01-01	51.2419676079312
1981-01-01	50.8299738302344
1982-01-01	50.5338661447518
1983-01-01	50.3191908899516
1984-01-01	50.1505196619628
1985-01-01	50.0164533553522
1986-01-01	49.7626437232353
1987-01-01	49.5846413170988
1988-01-01	49.4754679251176
1989-01-01	49.4353321741020
1990-01-01	49.4638654214704
1991-01-01	49.4049447496841
1992-01-01	49.4210191916566
1993-01-01	49.5039924727369
1994-01-01	49.6449886661231
1995-01-01	49.8339524025960
1996-01-01	49.8590681637310
1997-01-01	49.9569267246140
1998-01-01	50.1045791652703
1999-01-01	50.2780672819390
2000-01-01	50.4652762737788
2001-01-01	50.4862328015192
2002-01-01	50.5552057658361
2003-01-01	50.6603951236469
2004-01-01	50.7907828123238
2005-01-01	50.9382331751097
2006-01-01	50.9353015005882
2007-01-01	50.9747705255276
2008-01-01	51.0504008039360
2009-01-01	51.1619995351725
2010-01-01	51.3087322015452
2011-01-01	51.3567112451362
2012-01-01	51.4673153738386
2013-01-01	51.6236923658868
2014-01-01	51.8095298316380
2015-01-01	52.0181855688683
2016-01-01	52.2026545237902
2017-01-01	52.4099608917282