Year	Percent of Total
1960-01-01	49.5360790673791
1961-01-01	49.5809959818841
1962-01-01	49.7797555369482
1963-01-01	50.0887191431611
1964-01-01	50.4717504717505
1965-01-01	50.9343950953150
1966-01-01	51.3826722986874
1967-01-01	51.9033106311986
1968-01-01	52.5039487504309
1969-01-01	53.1976344921497
1970-01-01	53.9766276230527
1971-01-01	54.5527566727677
1972-01-01	55.2058347795009
1973-01-01	55.9155542160630
1974-01-01	56.6467629309430
1975-01-01	57.3671294409421
1976-01-01	57.5107230392157
1977-01-01	57.6705072552189
1978-01-01	57.8453913628568
1979-01-01	58.0197831830073
1980-01-01	58.1734893861520
1981-01-01	58.2562542725688
1982-01-01	58.3181931104254
1983-01-01	58.3049675294832
1984-01-01	58.2302681740690
1985-01-01	58.1741868670617
1986-01-01	58.1874836475781
1987-01-01	58.2415740067200
1988-01-01	58.3427973059148
1989-01-01	58.4788800812559
1990-01-01	58.6286829493239
1991-01-01	58.8993749600597
1992-01-01	59.1753734901569
1993-01-01	59.4998053047180
1994-01-01	59.9135133158410
1995-01-01	60.4109875202773
1996-01-01	60.5257522218653
1997-01-01	60.7599071715057
1998-01-01	61.0444637424014
1999-01-01	61.3054777840877
2000-01-01	61.5388123857435
2001-01-01	62.4718441498468
2002-01-01	63.2702824966807
2003-01-01	63.9919277810705
2004-01-01	64.6913194045609
2005-01-01	65.3572510668434
2006-01-01	65.3855218265167
2007-01-01	65.5081623167851
2008-01-01	65.7048165627149
2009-01-01	65.9375304442543
2010-01-01	66.1709401709402
2011-01-01	66.0010656382412
2012-01-01	65.8582456879381
2013-01-01	65.7190112706956
2014-01-01	65.5722584854923
2015-01-01	65.4243853885393
2016-01-01	65.3731808269171
2017-01-01	65.3055432235379