Year	Percent of Total
1960-01-01	56.7795154662373
1961-01-01	56.5880413005923
1962-01-01	56.2485036166645
1963-01-01	55.8980739696583
1964-01-01	55.7062576700802
1965-01-01	55.7257045865179
1966-01-01	55.5420122359423
1967-01-01	55.6166173559090
1968-01-01	55.8374793176048
1969-01-01	56.0527348330862
1970-01-01	56.1997553490383
1971-01-01	56.2320757057010
1972-01-01	56.2712857742404
1973-01-01	56.3315204529666
1974-01-01	56.4683240853517
1975-01-01	56.7170727929938
1976-01-01	57.0390952323471
1977-01-01	57.4507803484739
1978-01-01	57.9458709034647
1979-01-01	58.5004417502677
1980-01-01	59.0880655380899
1981-01-01	59.7249067726807
1982-01-01	60.3333999706287
1983-01-01	60.9176712061182
1984-01-01	61.4736730501991
1985-01-01	61.9833770208245
1986-01-01	62.3007879420058
1987-01-01	62.5842584700646
1988-01-01	62.8304133074310
1989-01-01	63.0582646239117
1990-01-01	63.2947037103305
1991-01-01	63.3465686536100
1992-01-01	63.5456139492262
1993-01-01	63.8264602123133
1994-01-01	64.1068882417674
1995-01-01	64.3579103830735
1996-01-01	64.8421674129252
1997-01-01	65.1917587061173
1998-01-01	65.5061780199189
1999-01-01	65.9197750713066
2000-01-01	66.4792851383970
2001-01-01	66.9892726565393
2002-01-01	67.6281977750651
2003-01-01	68.3386857778450
2004-01-01	69.0136335292642
2005-01-01	69.5904561655025
2006-01-01	70.0048449661981
2007-01-01	70.3586621817607
2008-01-01	70.6295465687271
2009-01-01	70.8142710246823
2010-01-01	70.9151894024797
2011-01-01	70.9298599036870
2012-01-01	70.8674236976164
2013-01-01	70.7364918747682
2014-01-01	70.5533998575385
2015-01-01	70.3311114918519
2016-01-01	70.0303893420388
2017-01-01	69.7173645342795