Year	Percent of Total
1960-01-01	8.57763005302289
1961-01-01	8.59707696771971
1962-01-01	8.60750813084818
1963-01-01	8.61028779349144
1964-01-01	8.60341742500435
1965-01-01	8.58754836727634
1966-01-01	8.51393628916375
1967-01-01	8.43312322160933
1968-01-01	8.35186900834866
1969-01-01	8.27867730719350
1970-01-01	8.22041302642774
1971-01-01	8.32308875535504
1972-01-01	8.42026605956649
1973-01-01	8.51992942836352
1974-01-01	8.63369093711279
1975-01-01	8.76837493418867
1976-01-01	8.92163368745267
1977-01-01	9.10334993515081
1978-01-01	9.29576000164369
1979-01-01	9.47081517741498
1980-01-01	9.61469751686006
1981-01-01	9.77436119864994
1982-01-01	9.88783041626374
1983-01-01	9.98102685930290
1984-01-01	10.09154390195680
1985-01-01	10.23827432065690
1986-01-01	10.37711736223900
1987-01-01	10.54479762607480
1988-01-01	10.72647713528360
1989-01-01	10.90147063885380
1990-01-01	11.06252168611900
1991-01-01	11.26248373511760
1992-01-01	11.44355456164000
1993-01-01	11.60451413115460
1994-01-01	11.74628358063980
1995-01-01	11.87148038781100
1996-01-01	11.98219540233970
1997-01-01	12.07735953390340
1998-01-01	12.16290665251540
1999-01-01	12.24841646402440
2000-01-01	12.34462457640860
2001-01-01	12.43706513619900
2002-01-01	12.53805418391020
2003-01-01	12.64911682871860
2004-01-01	12.76805306322620
2005-01-01	12.89425617584120
2006-01-01	12.95920608181180
2007-01-01	13.02376836712520
2008-01-01	13.10971965646190
2009-01-01	13.24619210415920
2010-01-01	13.44754698720580
2011-01-01	13.70789391844650
2012-01-01	14.01699310165450
2013-01-01	14.35065392541200
2014-01-01	14.67564099309090
2015-01-01	14.97702730252620
2016-01-01	15.25289390864110
2017-01-01	15.50357883403980