Year	Percent of Total
1960-01-01	53.8318968665547
1961-01-01	53.8824408381694
1962-01-01	53.8258880272210
1963-01-01	53.6600881154139
1964-01-01	53.4473215754910
1965-01-01	53.2687392005941
1966-01-01	53.5336075318038
1967-01-01	53.8624851745310
1968-01-01	54.1717362113638
1969-01-01	54.3708294773757
1970-01-01	54.4598887537348
1971-01-01	55.1083324226546
1972-01-01	55.3995467810773
1973-01-01	55.4973331570131
1974-01-01	55.6442768464443
1975-01-01	55.9587467307631
1976-01-01	56.2892038444392
1977-01-01	56.9389836183673
1978-01-01	57.7377141921365
1979-01-01	58.4273316766328
1980-01-01	58.8908245949654
1981-01-01	59.6236698917343
1982-01-01	59.9818408807173
1983-01-01	60.1482323579958
1984-01-01	60.3860617785797
1985-01-01	60.8137647164095
1986-01-01	61.0690374731842
1987-01-01	61.6254370503671
1988-01-01	62.3235411727166
1989-01-01	62.9059476114656
1990-01-01	63.2486268023220
1991-01-01	63.6556166607945
1992-01-01	63.7453312992703
1993-01-01	63.6822598786717
1994-01-01	63.7238804617699
1995-01-01	63.9839371765126
1996-01-01	64.0269213150569
1997-01-01	64.3178729483918
1998-01-01	64.7448803695787
1999-01-01	65.1162236180562
2000-01-01	65.3425761187015
2001-01-01	65.9831428241543
2002-01-01	66.5257458184676
2003-01-01	67.0405959220386
2004-01-01	67.5933103067660
2005-01-01	68.1836543163381
2006-01-01	68.4730369532204
2007-01-01	68.8041877964993
2008-01-01	69.2657366724409
2009-01-01	69.8604504362333
2010-01-01	70.5134245299752
2011-01-01	70.6370987101984
2012-01-01	70.8495614707060
2013-01-01	71.0393913688898
2014-01-01	71.1007433883962
2015-01-01	71.0147400203703
2016-01-01	70.8584676100114
2017-01-01	70.5502060142503