Year	Percent of Total
1960-01-01	52.1477604146767
1961-01-01	53.0942236400014
1962-01-01	53.9255919159889
1963-01-01	54.5956514705900
1964-01-01	55.1452217733355
1965-01-01	55.6705970536065
1966-01-01	55.7139396949642
1967-01-01	55.9766531440855
1968-01-01	56.3445818202626
1969-01-01	56.6959105565293
1970-01-01	56.9706488314259
1971-01-01	57.6775574104752
1972-01-01	58.3813359508752
1973-01-01	59.0232936387760
1974-01-01	59.5950724386224
1975-01-01	60.1138993808081
1976-01-01	60.2476417623905
1977-01-01	60.2990503650947
1978-01-01	60.3488620475377
1979-01-01	60.4319797335765
1980-01-01	60.5432618359925
1981-01-01	60.7096181051054
1982-01-01	60.8956541448459
1983-01-01	61.1293310521254
1984-01-01	61.4127499094479
1985-01-01	61.7373346244553
1986-01-01	62.0397232957453
1987-01-01	62.3383922077119
1988-01-01	62.6237376754050
1989-01-01	62.8801163300952
1990-01-01	63.1002778587114
1991-01-01	63.3696429230088
1992-01-01	63.6104915692747
1993-01-01	63.8279783123444
1994-01-01	64.0402557874257
1995-01-01	64.2594225291837
1996-01-01	64.3867810387049
1997-01-01	64.5609510460690
1998-01-01	64.7688611468970
1999-01-01	64.9662029670613
2000-01-01	65.1210423450024
2001-01-01	65.2167539889792
2002-01-01	65.2919578043155
2003-01-01	65.3643734744940
2004-01-01	65.4624732447312
2005-01-01	65.5918270547159
2006-01-01	65.6944278374579
2007-01-01	65.8249712035860
2008-01-01	65.9996766411798
2009-01-01	66.2042099856400
2010-01-01	66.4076909230867
2011-01-01	66.4682933619352
2012-01-01	66.5425673468240
2013-01-01	66.6346049838928
2014-01-01	66.7361096960781
2015-01-01	66.8284913853176
2016-01-01	66.8812397710627
2017-01-01	66.8950960257769