Year	Percent of Total
1960-01-01	54.6687046921055
1961-01-01	54.4405510006043
1962-01-01	54.2462388604197
1963-01-01	54.0878825765693
1964-01-01	53.9748557754456
1965-01-01	53.9106967830975
1966-01-01	53.7081221861922
1967-01-01	53.5756277089406
1968-01-01	53.4867174604207
1969-01-01	53.4048369082923
1970-01-01	53.3084994054209
1971-01-01	53.0764514889505
1972-01-01	52.8330526221877
1973-01-01	52.5932334167271
1974-01-01	52.3865642580198
1975-01-01	52.2281864508493
1976-01-01	51.6084584092989
1977-01-01	51.0723319704212
1978-01-01	50.6097347303501
1979-01-01	50.2047968878944
1980-01-01	49.8582956771788
1981-01-01	49.6317187874663
1982-01-01	49.4883402154178
1983-01-01	49.4206262065470
1984-01-01	49.4136610231728
1985-01-01	49.4478804356345
1986-01-01	50.1759395170209
1987-01-01	50.8881291182112
1988-01-01	51.5796309473641
1989-01-01	52.2633100307148
1990-01-01	52.9438916739474
1991-01-01	53.2168733881862
1992-01-01	53.5352287508728
1993-01-01	53.8807794700327
1994-01-01	54.2324166406302
1995-01-01	54.5837489028060
1996-01-01	54.8230899818282
1997-01-01	55.1085449978795
1998-01-01	55.4302908593225
1999-01-01	55.7903427371394
2000-01-01	56.1968706710045
2001-01-01	56.2457204090203
2002-01-01	56.3221817733330
2003-01-01	56.4464758989900
2004-01-01	56.6342396184007
2005-01-01	56.8832927532581
2006-01-01	57.1076316293840
2007-01-01	57.3754696706356
2008-01-01	57.6676042964809
2009-01-01	57.9433234754614
2010-01-01	58.1722092611255
2011-01-01	58.5338828256277
2012-01-01	58.8267590839662
2013-01-01	59.0642429160983
2014-01-01	59.2802928057117
2015-01-01	59.4961742871031
2016-01-01	59.5939126826371
2017-01-01	59.7523318785979