Year	Percent of Total
1960-01-01	56.5466440960257
1961-01-01	56.0332760010222
1962-01-01	55.5768828422782
1963-01-01	55.1653517967603
1964-01-01	54.7987915651185
1965-01-01	54.4845435141574
1966-01-01	54.1297829378641
1967-01-01	53.8281955606068
1968-01-01	53.6016096956666
1969-01-01	53.4772579031264
1970-01-01	53.4620939753618
1971-01-01	53.3753549528562
1972-01-01	53.4201603801264
1973-01-01	53.5651940372191
1974-01-01	53.7678631751744
1975-01-01	54.0050831478186
1976-01-01	54.1762899661214
1977-01-01	54.3935762773481
1978-01-01	54.6565138024682
1979-01-01	54.9704423046440
1980-01-01	55.3336314545021
1981-01-01	55.6468177924801
1982-01-01	56.0052940248086
1983-01-01	56.4043662100579
1984-01-01	56.8440986654110
1985-01-01	57.3243580129071
1986-01-01	57.7341287909097
1987-01-01	58.2108445952641
1988-01-01	58.7303011602522
1989-01-01	59.2597116419760
1990-01-01	59.7815396027028
1991-01-01	60.2700825804466
1992-01-01	60.7293262746075
1993-01-01	61.1815726299777
1994-01-01	61.6620429911795
1995-01-01	62.1858598790851
1996-01-01	62.6365129458554
1997-01-01	63.1421821604986
1998-01-01	63.6733085177074
1999-01-01	64.1748236860681
2000-01-01	64.6045716395895
2001-01-01	64.7667696338641
2002-01-01	64.8822984531346
2003-01-01	64.9714008303077
2004-01-01	65.0605180164203
2005-01-01	65.1615253364908
2006-01-01	65.4209090097216
2007-01-01	65.6580715922722
2008-01-01	65.8659865640848
2009-01-01	66.0370654060447
2010-01-01	66.1826386647732
2011-01-01	66.4016164324745
2012-01-01	66.5550871663383
2013-01-01	66.6872534489761
2014-01-01	66.8460898356279
2015-01-01	67.0462233937479
2016-01-01	67.1458306933772
2017-01-01	67.3241765216886