Year	Percent of Total
1960-01-01	55.2462261232988
1961-01-01	55.0596380387800
1962-01-01	54.9126522541310
1963-01-01	54.8130533411280
1964-01-01	54.7766633421238
1965-01-01	54.8053088356640
1966-01-01	54.6769919268480
1967-01-01	54.6361116896016
1968-01-01	54.6529091241887
1969-01-01	54.6878112556928
1970-01-01	54.7191890576947
1971-01-01	54.5779278961287
1972-01-01	54.4598588938980
1973-01-01	54.3643362231942
1974-01-01	54.3079574652328
1975-01-01	54.3067404165125
1976-01-01	53.7485483093915
1977-01-01	53.2609742455137
1978-01-01	52.8348359322314
1979-01-01	52.4441528898822
1980-01-01	52.0708108665547
1981-01-01	51.9824864888937
1982-01-01	51.9283544070078
1983-01-01	51.9065311891740
1984-01-01	51.9191073117998
1985-01-01	51.9603850214946
1986-01-01	51.9575292109236
1987-01-01	51.9901474022980
1988-01-01	52.0489914297334
1989-01-01	52.1232802565624
1990-01-01	52.2075993454929
1991-01-01	52.0465298181103
1992-01-01	51.9339067063229
1993-01-01	51.8752271114880
1994-01-01	51.8917048844185
1995-01-01	52.0036282521384
1996-01-01	51.9736220996615
1997-01-01	52.0927737045980
1998-01-01	52.3335280617648
1999-01-01	52.6591575652073
2000-01-01	53.0537195851466
2001-01-01	53.5695737868654
2002-01-01	54.0990960427106
2003-01-01	54.6759513489720
2004-01-01	55.3335139872948
2005-01-01	56.0683597884333
2006-01-01	56.8820738556518
2007-01-01	57.7055279457903
2008-01-01	58.5181397147149
2009-01-01	59.2937037429560
2010-01-01	60.0216224904639
2011-01-01	60.5697461761586
2012-01-01	61.1099567291212
2013-01-01	61.6151648218655
2014-01-01	62.0495538818596
2015-01-01	62.4025449105615
2016-01-01	62.7756644259334
2017-01-01	63.0858714290714