Year	Percent of Total
1960-01-01	6.77609320868987
1961-01-01	6.97054695114831
1962-01-01	7.18889768792045
1963-01-01	7.42584069544762
1964-01-01	7.67466666543877
1965-01-01	7.93249247396801
1966-01-01	8.18986443589648
1967-01-01	8.44807858740489
1968-01-01	8.70606036779646
1969-01-01	8.95403777542593
1970-01-01	9.18344572986804
1971-01-01	9.39731351092751
1972-01-01	9.56575316557301
1973-01-01	9.70508318881887
1974-01-01	9.84278794757190
1975-01-01	9.99175177904868
1976-01-01	10.15952338953730
1977-01-01	10.34889872162720
1978-01-01	10.50845957396820
1979-01-01	10.56369941524150
1980-01-01	10.48425460566120
1981-01-01	10.31030061296230
1982-01-01	10.01223913013490
1983-01-01	9.67552505008333
1984-01-01	9.41908661196628
1985-01-01	9.30628602085856
1986-01-01	9.40701221683898
1987-01-01	9.60785324175918
1988-01-01	9.85706429170204
1989-01-01	10.07988905605750
1990-01-01	10.23646986434980
1991-01-01	10.40756342486250
1992-01-01	10.52247190062440
1993-01-01	10.59903344059170
1994-01-01	10.66229887732300
1995-01-01	10.72676435734920
1996-01-01	10.87168148495350
1997-01-01	11.01254933035370
1998-01-01	11.13908631549140
1999-01-01	11.23465737679770
2000-01-01	11.29159427182970
2001-01-01	11.40404288439680
2002-01-01	11.47654307636410
2003-01-01	11.52626185071310
2004-01-01	11.57557877986500
2005-01-01	11.63767930989710
2006-01-01	11.77429235047020
2007-01-01	11.92191801680740
2008-01-01	12.08259675753530
2009-01-01	12.25799749996250
2010-01-01	12.45233882538590
2011-01-01	12.71775338563180
2012-01-01	12.99911206611690
2013-01-01	13.30736774971290
2014-01-01	13.65753203526480
2015-01-01	14.05729541828590
2016-01-01	14.54686421447490
2017-01-01	15.07018974378370