Year	Percent of Total
1960-01-01	53.7078516743553
1961-01-01	53.5014859028965
1962-01-01	53.3235889380061
1963-01-01	53.2031309653348
1964-01-01	53.1799591009603
1965-01-01	53.2700571821943
1966-01-01	53.2783628340703
1967-01-01	53.4481193841874
1968-01-01	53.7241467987522
1969-01-01	54.0379298355738
1970-01-01	54.3585579344938
1971-01-01	54.6652081975987
1972-01-01	54.9747603436417
1973-01-01	55.3015901715466
1974-01-01	55.6676885661641
1975-01-01	56.0734805844324
1976-01-01	56.4192080210587
1977-01-01	56.7828228737591
1978-01-01	57.1577369327288
1979-01-01	57.5319116207545
1980-01-01	57.8949565607017
1981-01-01	58.1134752315125
1982-01-01	58.3579470121337
1983-01-01	58.6122710264779
1984-01-01	58.8694362447711
1985-01-01	59.1345616261401
1986-01-01	59.3310000102239
1987-01-01	59.5761053199168
1988-01-01	59.8585215149988
1989-01-01	60.1668751068267
1990-01-01	60.4978348319001
1991-01-01	60.8677000272220
1992-01-01	61.2282917013982
1993-01-01	61.6065485345690
1994-01-01	62.0315191767518
1995-01-01	62.5074693487748
1996-01-01	62.9375109368070
1997-01-01	63.4019260621572
1998-01-01	63.8837257707910
1999-01-01	64.3586230578702
2000-01-01	64.8145136483624
2001-01-01	65.1693419777264
2002-01-01	65.5430173776256
2003-01-01	65.9206660263520
2004-01-01	66.2895816744340
2005-01-01	66.6470157365425
2006-01-01	67.0291911834869
2007-01-01	67.3822426136309
2008-01-01	67.7160034834666
2009-01-01	68.0432239357036
2010-01-01	68.3638397636492
2011-01-01	68.6488346919347
2012-01-01	68.9090444874814
2013-01-01	69.1449211513865
2014-01-01	69.3531017909607
2015-01-01	69.5292975929339
2016-01-01	69.6163989839485
2017-01-01	69.7004793550836