Year	Percent of Total
1960-01-01	61.0339042016306
1961-01-01	61.0371672461457
1962-01-01	61.2596825999008
1963-01-01	61.6085562802802
1964-01-01	61.9296349648886
1965-01-01	62.1457317005466
1966-01-01	62.2446135754257
1967-01-01	62.3035462985549
1968-01-01	62.3339637313508
1969-01-01	62.3862592995865
1970-01-01	62.4943056587773
1971-01-01	62.6513507979810
1972-01-01	62.8732384066565
1973-01-01	63.1618200095866
1974-01-01	63.5144802136607
1975-01-01	63.9259663483003
1976-01-01	64.3277766943061
1977-01-01	64.7712499829949
1978-01-01	65.2533312929149
1979-01-01	65.7660293392523
1980-01-01	66.2960197308320
1981-01-01	66.8156169362496
1982-01-01	67.3249101430220
1983-01-01	67.8071349984703
1984-01-01	68.2380183945897
1985-01-01	68.5962793447875
1986-01-01	68.7789840265200
1987-01-01	68.9263224912616
1988-01-01	69.0254485605087
1989-01-01	69.0709684231694
1990-01-01	69.0666460502886
1991-01-01	69.0000722890654
1992-01-01	68.9016819485763
1993-01-01	68.7738464341709
1994-01-01	68.6341573232560
1995-01-01	68.4982225391232
1996-01-01	68.3413848838177
1997-01-01	68.2108463652492
1998-01-01	68.1081126739346
1999-01-01	68.0245230927958
2000-01-01	67.9500706634883
2001-01-01	67.8734587605008
2002-01-01	67.7787236842391
2003-01-01	67.6776628730005
2004-01-01	67.5957265044377
2005-01-01	67.5459783549471
2006-01-01	67.4203243727487
2007-01-01	67.3671549911747
2008-01-01	67.3322053453209
2009-01-01	67.2366738145103
2010-01-01	67.0402783877664
2011-01-01	66.7788592007099
2012-01-01	66.4184221960743
2013-01-01	66.0086501546138
2014-01-01	65.6303354609850
2015-01-01	65.3242002139623
2016-01-01	65.0402741337220
2017-01-01	64.8078726278530