Year	Percent of Total
1960-01-01	54.0487232449950
1961-01-01	53.4792310543291
1962-01-01	52.9088914102430
1963-01-01	52.3929979281190
1964-01-01	52.0142701617233
1965-01-01	51.7975053118117
1966-01-01	51.4111710634027
1967-01-01	51.2090011634098
1968-01-01	51.1385018602238
1969-01-01	51.1197498375878
1970-01-01	51.1061454722675
1971-01-01	50.8617977611223
1972-01-01	50.6768471573225
1973-01-01	50.5505467386159
1974-01-01	50.4918061798747
1975-01-01	50.4993100870749
1976-01-01	50.3436634111834
1977-01-01	50.2759008192380
1978-01-01	50.2820216912845
1979-01-01	50.3500725884072
1980-01-01	50.4695376716002
1981-01-01	50.4251146288544
1982-01-01	50.4659508222162
1983-01-01	50.5672128170453
1984-01-01	50.7027900988787
1985-01-01	50.8588417840919
1986-01-01	50.9009652129226
1987-01-01	50.9753794086528
1988-01-01	51.0857214335312
1989-01-01	51.2342463494766
1990-01-01	51.4122483227118
1991-01-01	51.4381319854215
1992-01-01	51.5139168623636
1993-01-01	51.6205802392970
1994-01-01	51.7328875740125
1995-01-01	51.8343425798121
1996-01-01	51.7869134371713
1997-01-01	51.7653859594613
1998-01-01	51.7683921665178
1999-01-01	51.8051701024981
2000-01-01	51.8820171948586
2001-01-01	51.8616522103407
2002-01-01	51.9180212103500
2003-01-01	52.0330437722569
2004-01-01	52.1881680932710
2005-01-01	52.3756969892768
2006-01-01	52.5636712360227
2007-01-01	52.7702105274478
2008-01-01	53.0084786469051
2009-01-01	53.2985147979829
2010-01-01	53.6440011270994
2011-01-01	53.9693272827305
2012-01-01	54.3519715528641
2013-01-01	54.7630331691632
2014-01-01	55.1609316246458
2015-01-01	55.5225680454738
2016-01-01	55.8286711015595
2017-01-01	56.1008678030237