Year	Percent of Total
1960-01-01	51.7702387079526
1961-01-01	51.5804399830002
1962-01-01	51.4471857684311
1963-01-01	51.3571772517061
1964-01-01	51.2993071255695
1965-01-01	51.2655333230636
1966-01-01	51.0723824736140
1967-01-01	50.9352613830214
1968-01-01	50.8382711746253
1969-01-01	50.7664944481893
1970-01-01	50.7116430162327
1971-01-01	50.5196454879324
1972-01-01	50.3789378805028
1973-01-01	50.2780871454909
1974-01-01	50.2071259438583
1975-01-01	50.1591673676223
1976-01-01	50.0224630988646
1977-01-01	49.9398563441603
1978-01-01	49.9054618653260
1979-01-01	49.9197739114773
1980-01-01	49.9833809731650
1981-01-01	49.9632601264235
1982-01-01	50.0157689847588
1983-01-01	50.1284166049468
1984-01-01	50.2913785727913
1985-01-01	50.5004042082750
1986-01-01	50.6315561900661
1987-01-01	50.8220395291660
1988-01-01	51.0568330790972
1989-01-01	51.3104570953340
1990-01-01	51.5602610535553
1991-01-01	51.8133066904379
1992-01-01	52.0484274894482
1993-01-01	52.2767702092884
1994-01-01	52.5232456815682
1995-01-01	52.8046317580734
1996-01-01	52.7999825709397
1997-01-01	52.8591050981346
1998-01-01	52.9570548504508
1999-01-01	53.0544282224232
2000-01-01	53.1308577978377
2001-01-01	53.1650182206087
2002-01-01	53.1907788699027
2003-01-01	53.2241262586992
2004-01-01	53.2953430824889
2005-01-01	53.4193321060611
2006-01-01	53.3993097239275
2007-01-01	53.4282571320472
2008-01-01	53.4989520412620
2009-01-01	53.5970378434940
2010-01-01	53.7158229362371
2011-01-01	53.9213287656828
2012-01-01	54.1659738853297
2013-01-01	54.4424467918762
2014-01-01	54.7425052360473
2015-01-01	55.0566949433063
2016-01-01	55.3343014603666
2017-01-01	55.6294831932141