Year	Percent of Total
1960-01-01	51.8994401117576
1961-01-01	51.6659792394853
1962-01-01	51.3609702278673
1963-01-01	51.0588277567645
1964-01-01	50.8724243391664
1965-01-01	50.8454379795963
1966-01-01	50.7808353612909
1967-01-01	50.8635646383068
1968-01-01	51.0523117985184
1969-01-01	51.2848557885843
1970-01-01	51.5285481645450
1971-01-01	51.6526360513600
1972-01-01	51.8339679602956
1973-01-01	52.0548657907935
1974-01-01	52.3067115059473
1975-01-01	52.5870528785351
1976-01-01	52.7936530620460
1977-01-01	53.0400174445237
1978-01-01	53.3246152019577
1979-01-01	53.6497512496698
1980-01-01	54.0137743067244
1981-01-01	54.3348843984390
1982-01-01	54.6899536991805
1983-01-01	55.0709121421931
1984-01-01	55.4667397119434
1985-01-01	55.8672422299455
1986-01-01	56.1906051889235
1987-01-01	56.5250640011305
1988-01-01	56.8636504772067
1989-01-01	57.2024190325774
1990-01-01	57.5403761818132
1991-01-01	57.8047202033460
1992-01-01	58.0897388271091
1993-01-01	58.3852439211695
1994-01-01	58.6812336271072
1995-01-01	58.9749927953846
1996-01-01	59.2179007639762
1997-01-01	59.4538294487888
1998-01-01	59.6960263928835
1999-01-01	59.9642978440224
2000-01-01	60.2664935991301
2001-01-01	60.5289838637708
2002-01-01	60.8337324033091
2003-01-01	61.1617835629527
2004-01-01	61.4802962653280
2005-01-01	61.7696037628193
2006-01-01	62.1045242234104
2007-01-01	62.3880421131237
2008-01-01	62.6410878181384
2009-01-01	62.8958956931920
2010-01-01	63.1650271950740
2011-01-01	63.3950711438192
2012-01-01	63.6530843145370
2013-01-01	63.9095933498779
2014-01-01	64.1233992441228
2015-01-01	64.2765204559262
2016-01-01	64.3928178998098
2017-01-01	64.4586919178498