Year	Percent of Total
1960-01-01	56.5295880004455
1961-01-01	56.2551864722917
1962-01-01	55.9038003294865
1963-01-01	55.5666442755022
1964-01-01	55.3588224857857
1965-01-01	55.3188758727081
1966-01-01	55.1259922648052
1967-01-01	55.1327807937049
1968-01-01	55.2637568758377
1969-01-01	55.4154398619029
1970-01-01	55.5422308169543
1971-01-01	55.5607772853100
1972-01-01	55.6027228118851
1973-01-01	55.6735695242891
1974-01-01	55.8037249470587
1975-01-01	56.0105606298984
1976-01-01	56.1985357875392
1977-01-01	56.4612583865368
1978-01-01	56.7871527777476
1979-01-01	57.1534219830033
1980-01-01	57.5392528903751
1981-01-01	57.8989661466490
1982-01-01	58.2526009935756
1983-01-01	58.6017212325634
1984-01-01	58.9473825164128
1985-01-01	59.2832820911220
1986-01-01	59.4628308139170
1987-01-01	59.6560653543746
1988-01-01	59.8530610766980
1989-01-01	60.0546586030709
1990-01-01	60.2654153611617
1991-01-01	60.3514367072193
1992-01-01	60.5292647959984
1993-01-01	60.7674852639295
1994-01-01	61.0284807989891
1995-01-01	61.2986688066264
1996-01-01	61.6645313111975
1997-01-01	61.9855284447075
1998-01-01	62.3078684578051
1999-01-01	62.6904699740159
2000-01-01	63.1487425602982
2001-01-01	63.5297294833106
2002-01-01	63.9799975727390
2003-01-01	64.4693935063972
2004-01-01	64.9438812029353
2005-01-01	65.3721687282010
2006-01-01	65.6927796864401
2007-01-01	65.9867888764022
2008-01-01	66.2424137624693
2009-01-01	66.4573340830863
2010-01-01	66.6313379323962
2011-01-01	66.7380559089276
2012-01-01	66.8138773018406
2013-01-01	66.8591803139046
2014-01-01	66.8770044347450
2015-01-01	66.8707151257874
2016-01-01	66.8029765945500
2017-01-01	66.7260486195866