Year	Percent of Total
1960-01-01	50.3450563528497
1961-01-01	49.8684967305663
1962-01-01	49.2801902548835
1963-01-01	48.6872803363562
1964-01-01	48.2426794811975
1965-01-01	48.0090088581523
1966-01-01	47.9137278254772
1967-01-01	47.9935371173522
1968-01-01	48.2011754740420
1969-01-01	48.4557033430319
1970-01-01	48.7089507286547
1971-01-01	48.9394536060525
1972-01-01	49.1974664629426
1973-01-01	49.4597351765490
1974-01-01	49.7086403004667
1975-01-01	49.9331589654170
1976-01-01	50.1541635824236
1977-01-01	50.3584378076208
1978-01-01	50.5444784035964
1979-01-01	50.7217636796983
1980-01-01	50.8971610874607
1981-01-01	50.8616646619742
1982-01-01	50.8621242525948
1983-01-01	50.9025727882005
1984-01-01	50.9984434878380
1985-01-01	51.1668351394399
1986-01-01	51.3231877796888
1987-01-01	51.6062465495122
1988-01-01	51.9896022331847
1989-01-01	52.4385200623459
1990-01-01	52.9346576559316
1991-01-01	53.5356394403736
1992-01-01	54.1257822840944
1993-01-01	54.7379963644708
1994-01-01	55.4186224652915
1995-01-01	56.1790434480025
1996-01-01	56.7238133236911
1997-01-01	57.3721861098474
1998-01-01	58.0782511042899
1999-01-01	58.7763594927117
2000-01-01	59.4334448083132
2001-01-01	59.8975460629596
2002-01-01	60.3479979527549
2003-01-01	60.7821479223139
2004-01-01	61.2066166301323
2005-01-01	61.6215086116781
2006-01-01	62.0681145375478
2007-01-01	62.4726939940890
2008-01-01	62.8414402129934
2009-01-01	63.1815431424701
2010-01-01	63.4920634920635
2011-01-01	63.7545525142358
2012-01-01	63.9880535007885
2013-01-01	64.1863522177752
2014-01-01	64.3489981660751
2015-01-01	64.4824341152011
2016-01-01	64.5535182601122
2017-01-01	64.6527562322700