Year	Percent of Total
1960-01-01	61.8912064489246
1961-01-01	61.5617444219872
1962-01-01	61.3125384950354
1963-01-01	61.1166745760414
1964-01-01	60.9422878296413
1965-01-01	60.7686977358214
1966-01-01	60.3752232484329
1967-01-01	60.0296484616926
1968-01-01	59.7201138771421
1969-01-01	59.4426992880223
1970-01-01	59.1966352492213
1971-01-01	58.5206678731859
1972-01-01	57.9456324424300
1973-01-01	57.4445944020454
1974-01-01	56.9914056315730
1975-01-01	56.5747188002143
1976-01-01	56.0609849797370
1977-01-01	55.6051056758214
1978-01-01	55.2043089997294
1979-01-01	54.8646373393785
1980-01-01	54.5828824714500
1981-01-01	54.1904821779940
1982-01-01	53.8756348983837
1983-01-01	53.6236377289829
1984-01-01	53.4188938512504
1985-01-01	53.2496069679611
1986-01-01	52.9806207775369
1987-01-01	52.7777999527862
1988-01-01	52.6255244282041
1989-01-01	52.5125671525174
1990-01-01	52.4369573162279
1991-01-01	52.3037180683750
1992-01-01	52.2282805601010
1993-01-01	52.2093952132033
1994-01-01	52.2479769293911
1995-01-01	52.3445016604719
1996-01-01	52.4507313324847
1997-01-01	52.6119559774635
1998-01-01	52.8239687711317
1999-01-01	53.0861370134072
2000-01-01	53.3940584280031
2001-01-01	53.7555287781667
2002-01-01	54.1735262965570
2003-01-01	54.6230610188940
2004-01-01	55.0744206332626
2005-01-01	55.5078446269259
2006-01-01	56.0825251722677
2007-01-01	56.6226808748094
2008-01-01	57.1230614724836
2009-01-01	57.5879436888138
2010-01-01	58.0174489851909
2011-01-01	58.3762545658744
2012-01-01	58.7321843993996
2013-01-01	59.0727524953625
2014-01-01	59.4000787967029
2015-01-01	59.7239110443354
2016-01-01	59.6572558852320
2017-01-01	59.6475695224570