Year	Percent of Total
1960-01-01	58.1757290647354
1961-01-01	57.2263886994007
1962-01-01	56.0914207514110
1963-01-01	54.9205042676252
1964-01-01	53.9299627552549
1965-01-01	53.2148160458991
1966-01-01	52.3040700515193
1967-01-01	51.7930158004963
1968-01-01	51.5193388473570
1969-01-01	51.2679779812496
1970-01-01	50.9488788536352
1971-01-01	50.6349796894575
1972-01-01	50.2293851857858
1973-01-01	49.8554358965551
1974-01-01	49.6929627891618
1975-01-01	49.8104620616618
1976-01-01	49.8800353746059
1977-01-01	50.2443655106327
1978-01-01	50.7864550665687
1979-01-01	51.3384328772981
1980-01-01	51.8156723811598
1981-01-01	52.1852925482052
1982-01-01	52.4954619016306
1983-01-01	52.7866692701249
1984-01-01	53.1226183668343
1985-01-01	53.5228247742706
1986-01-01	53.7748904650032
1987-01-01	54.0836937004726
1988-01-01	54.4494605481898
1989-01-01	54.8864366690830
1990-01-01	55.4075851191198
1991-01-01	55.5920011470217
1992-01-01	55.9806053215018
1993-01-01	56.4937698833510
1994-01-01	57.0364517192751
1995-01-01	57.5761769056139
1996-01-01	58.3835477238517
1997-01-01	59.0717109896626
1998-01-01	59.7401500261081
1999-01-01	60.5408637963236
2000-01-01	61.5373257096331
2001-01-01	62.5925292258457
2002-01-01	63.8220389997131
2003-01-01	65.1298391518844
2004-01-01	66.3409071976008
2005-01-01	67.3452351643376
2006-01-01	68.1105092548432
2007-01-01	68.6533393526182
2008-01-01	68.9920707909918
2009-01-01	69.1777015158403
2010-01-01	69.2339225480619
2011-01-01	68.9999623395266
2012-01-01	68.6674773099246
2013-01-01	68.2497724901860
2014-01-01	67.7899966346272
2015-01-01	67.3351972553787
2016-01-01	66.7487723781280
2017-01-01	66.3014643748129