Year	Percent of Total
1960-01-01	48.8953294357223
1961-01-01	48.9946900878910
1962-01-01	49.0214362972408
1963-01-01	49.0135338272828
1964-01-01	49.0267466693786
1965-01-01	49.0917650570581
1966-01-01	49.3150101194235
1967-01-01	49.5728914710196
1968-01-01	49.8459526794195
1969-01-01	50.1164320478694
1970-01-01	50.3878976891047
1971-01-01	50.7663017347839
1972-01-01	51.1790749859728
1973-01-01	51.5899436197674
1974-01-01	51.9527097806775
1975-01-01	52.2491169711376
1976-01-01	52.7093239716087
1977-01-01	53.0280458203807
1978-01-01	53.2563912522085
1979-01-01	53.4644893717268
1980-01-01	53.6806230212254
1981-01-01	53.8526270871441
1982-01-01	54.0710109753739
1983-01-01	54.2918171973918
1984-01-01	54.4573445687929
1985-01-01	54.5509781781599
1986-01-01	54.5682458110792
1987-01-01	54.5718421304585
1988-01-01	54.5722675461798
1989-01-01	54.5940932929588
1990-01-01	54.6552684051373
1991-01-01	54.7155370413632
1992-01-01	54.8095126802047
1993-01-01	54.9522424746284
1994-01-01	55.1577057656854
1995-01-01	55.4285894325593
1996-01-01	55.7152225124387
1997-01-01	56.0502246431170
1998-01-01	56.4323650946789
1999-01-01	56.8617629961649
2000-01-01	57.3367529748996
2001-01-01	57.7678788094012
2002-01-01	58.2766871721383
2003-01-01	58.8297862855411
2004-01-01	59.3763565660426
2005-01-01	59.8893209103486
2006-01-01	60.3927282197105
2007-01-01	60.8049668136568
2008-01-01	61.1682558812737
2009-01-01	61.5456808005827
2010-01-01	61.9609857006830
2011-01-01	62.3265371557933
2012-01-01	62.7543277633202
2013-01-01	63.1944526071262
2014-01-01	63.5700206208726
2015-01-01	63.8457301337723
2016-01-01	64.0841579300160
2017-01-01	64.2228345056749