Year	Percent of Total
1960-01-01	7.04843982945404
1961-01-01	7.16714101191943
1962-01-01	7.30299178326880
1963-01-01	7.45282641851787
1964-01-01	7.60651520230109
1965-01-01	7.76029453391183
1966-01-01	8.18557583944623
1967-01-01	8.62903694093123
1968-01-01	9.09900165369531
1969-01-01	9.61339866153679
1970-01-01	10.18268908213190
1971-01-01	10.46322929458120
1972-01-01	10.75527967818500
1973-01-01	11.04657210260080
1974-01-01	11.31773705163550
1975-01-01	11.56016198595390
1976-01-01	11.80143466865690
1977-01-01	12.01359641635460
1978-01-01	12.19708493711690
1979-01-01	12.35264142684180
1980-01-01	12.48130676991780
1981-01-01	12.54237887505850
1982-01-01	12.59554356790780
1983-01-01	12.64710284954300
1984-01-01	12.70057710655790
1985-01-01	12.75735635789570
1986-01-01	12.81833841578690
1987-01-01	12.90559927757280
1988-01-01	13.04670006572850
1989-01-01	13.26008050387210
1990-01-01	13.54529919733910
1991-01-01	13.73465319498600
1992-01-01	13.94475983495830
1993-01-01	14.18097413463100
1994-01-01	14.44628256653510
1995-01-01	14.73991774315010
1996-01-01	15.06350754422060
1997-01-01	15.39963560303080
1998-01-01	15.74061776402710
1999-01-01	16.07190485782760
2000-01-01	16.38417252589030
2001-01-01	16.74533577935980
2002-01-01	17.08557851486860
2003-01-01	17.39021966961200
2004-01-01	17.63830560483870
2005-01-01	17.82176483142860
2006-01-01	17.98179167581670
2007-01-01	18.06113349413500
2008-01-01	18.10740734805550
2009-01-01	18.19004969316210
2010-01-01	18.35014050753950
2011-01-01	18.57501725714480
2012-01-01	18.88460596381330
2013-01-01	19.24805455203910
2014-01-01	19.61211484416040
2015-01-01	19.94783290841340
2016-01-01	20.19065040635870
2017-01-01	20.39623924250070