Year	Percent of Total
1960-01-01	61.7606359608602
1961-01-01	61.7264314839485
1962-01-01	61.6066770137002
1963-01-01	61.4857357678715
1964-01-01	61.4822195858186
1965-01-01	61.6461637996720
1966-01-01	61.7935337993597
1967-01-01	62.1082599948298
1968-01-01	62.5348237947259
1969-01-01	62.9607445990009
1970-01-01	63.3100168082557
1971-01-01	63.6096803825016
1972-01-01	63.8181943836332
1973-01-01	63.9437853058842
1974-01-01	64.0151664892001
1975-01-01	64.0431642868866
1976-01-01	63.8556306972825
1977-01-01	63.6662526530155
1978-01-01	63.4924484041245
1979-01-01	63.3764409946468
1980-01-01	63.3529401522715
1981-01-01	63.4279474032034
1982-01-01	63.6207919367586
1983-01-01	63.8617784373532
1984-01-01	64.0579755278885
1985-01-01	64.1647302642759
1986-01-01	64.2100792675672
1987-01-01	64.1570939541863
1988-01-01	64.1002083128339
1989-01-01	64.1558713785438
1990-01-01	64.3743521263492
1991-01-01	64.5739922983255
1992-01-01	64.9402058497292
1993-01-01	65.4247239777574
1994-01-01	65.9534885628959
1995-01-01	66.4874513298372
1996-01-01	66.9210189890484
1997-01-01	67.3909390184456
1998-01-01	67.8930778791879
1999-01-01	68.4294704344881
2000-01-01	68.9949883418151
2001-01-01	69.5632560408266
2002-01-01	70.1011119312523
2003-01-01	70.6106573360993
2004-01-01	71.0939454782079
2005-01-01	71.5398864559731
2006-01-01	71.7928973772729
2007-01-01	72.0033951265633
2008-01-01	72.1547120352904
2009-01-01	72.2273645416471
2010-01-01	72.2125591242816
2011-01-01	72.0154932292910
2012-01-01	71.7865008205543
2013-01-01	71.4975493674806
2014-01-01	71.1226778033813
2015-01-01	70.6591341046800
2016-01-01	70.1544096874886
2017-01-01	69.5610337058356