Year	Percent of Total
1960-01-01	53.7851406267052
1961-01-01	54.4660833328007
1962-01-01	55.4749993651439
1963-01-01	56.7367151051986
1964-01-01	58.0516164561873
1965-01-01	59.2911946021887
1966-01-01	60.0962046727984
1967-01-01	60.9365863368874
1968-01-01	61.7541957573548
1969-01-01	62.4610659958678
1970-01-01	63.0061920858769
1971-01-01	63.7213429226626
1972-01-01	64.1093042205066
1973-01-01	64.3114937011850
1974-01-01	64.5306093265731
1975-01-01	64.8635002059965
1976-01-01	65.0674265061876
1977-01-01	65.4629706298167
1978-01-01	65.9272823665985
1979-01-01	66.2694223725163
1980-01-01	66.4105210727509
1981-01-01	66.3922211348838
1982-01-01	66.2956545314167
1983-01-01	66.1717664639201
1984-01-01	66.0850763698591
1985-01-01	66.0623260289350
1986-01-01	66.0074474365378
1987-01-01	65.9528907922912
1988-01-01	65.9236895121910
1989-01-01	65.9500637830987
1990-01-01	66.0443266352204
1991-01-01	66.0986373827300
1992-01-01	66.2323751760459
1993-01-01	66.4126875414678
1994-01-01	66.5957570967040
1995-01-01	66.7551044556343
1996-01-01	66.9917385525527
1997-01-01	67.1987995371709
1998-01-01	67.3928905159944
1999-01-01	67.6073183428347
2000-01-01	67.8622928998558
2001-01-01	67.9781037441595
2002-01-01	68.1547359476505
2003-01-01	68.3656943882980
2004-01-01	68.5654815842689
2005-01-01	68.7236809435896
2006-01-01	69.0904462714441
2007-01-01	69.3595792593170
2008-01-01	69.4920024846650
2009-01-01	69.4707097054668
2010-01-01	69.2888899569825
2011-01-01	69.0293450487252
2012-01-01	68.6655307054129
2013-01-01	68.2066694073895
2014-01-01	67.7068402377987
2015-01-01	67.2198888722592
2016-01-01	66.6533135209916
2017-01-01	66.1464365708450