Year	Percent of Total
1960-01-01	58.2424002333367
1961-01-01	58.0094315482886
1962-01-01	57.8898211732225
1963-01-01	57.8505629136588
1964-01-01	57.8627909612501
1965-01-01	57.9113926609615
1966-01-01	57.5340317720082
1967-01-01	57.2747362571563
1968-01-01	57.0975610883289
1969-01-01	56.9641051567240
1970-01-01	56.8488024369126
1971-01-01	56.3735464507522
1972-01-01	55.9679504079691
1973-01-01	55.6207461643676
1974-01-01	55.3371035994245
1975-01-01	55.1189160806927
1976-01-01	54.6108399859482
1977-01-01	54.2381651142018
1978-01-01	53.9629503720948
1979-01-01	53.7432075367775
1980-01-01	53.5594592209461
1981-01-01	53.1741279438489
1982-01-01	52.8630376306342
1983-01-01	52.6274603041329
1984-01-01	52.4718290499685
1985-01-01	52.3880985906226
1986-01-01	52.1243531526889
1987-01-01	51.9768169276877
1988-01-01	51.9276260154145
1989-01-01	51.9830011662636
1990-01-01	52.1755716162761
1991-01-01	52.0782691477228
1992-01-01	52.0718799667169
1993-01-01	52.1732528900362
1994-01-01	52.3641563994574
1995-01-01	52.5960046495536
1996-01-01	52.5865237544806
1997-01-01	52.6874163125616
1998-01-01	52.8472227645518
1999-01-01	52.9986797521206
2000-01-01	53.0768045988243
2001-01-01	53.0089275559505
2002-01-01	53.0073533208962
2003-01-01	53.0381385000891
2004-01-01	53.1087496633543
2005-01-01	53.2510989454753
2006-01-01	53.1943210550325
2007-01-01	53.1875845016231
2008-01-01	53.2525855698570
2009-01-01	53.3988615366086
2010-01-01	53.6187356008621
2011-01-01	53.7031368067357
2012-01-01	53.8836461697376
2013-01-01	54.1371024514456
2014-01-01	54.4358357670018
2015-01-01	54.7648239435403
2016-01-01	55.0596861356996
2017-01-01	55.3712533140529