Year	Percent of Total
1960-01-01	54.3054084652296
1961-01-01	53.9751834060991
1962-01-01	53.7375932555575
1963-01-01	53.5799341445868
1964-01-01	53.5042169856258
1965-01-01	53.5091348659942
1966-01-01	53.2626137108652
1967-01-01	53.1367292287799
1968-01-01	53.1028845948504
1969-01-01	53.1282353425964
1970-01-01	53.1906665412146
1971-01-01	52.9973726270231
1972-01-01	52.8781143175498
1973-01-01	52.8182319553746
1974-01-01	52.8086956038464
1975-01-01	52.8405545984173
1976-01-01	52.6829288478474
1977-01-01	52.6356101928364
1978-01-01	52.6618756715611
1979-01-01	52.7299011101621
1980-01-01	52.8312468650648
1981-01-01	52.4732973688284
1982-01-01	52.1681056612398
1983-01-01	51.9387475204832
1984-01-01	51.8254552357361
1985-01-01	51.8521256846194
1986-01-01	51.2065279643036
1987-01-01	50.7153712799791
1988-01-01	50.3495659660068
1989-01-01	50.0290858542286
1990-01-01	49.6841816989566
1991-01-01	50.3953216494739
1992-01-01	50.9879768159587
1993-01-01	51.4551859859213
1994-01-01	51.8425260517089
1995-01-01	52.1986426663600
1996-01-01	52.0362215409037
1997-01-01	51.9602276486495
1998-01-01	51.9492109952978
1999-01-01	51.9593577865152
2000-01-01	51.9605027472526
2001-01-01	51.7740615053464
2002-01-01	51.6209171553640
2003-01-01	51.4959984476024
2004-01-01	51.4083820938669
2005-01-01	51.3643934661596
2006-01-01	51.2061350331591
2007-01-01	51.1154235772073
2008-01-01	51.0815057436158
2009-01-01	51.0930573515298
2010-01-01	51.1437796444921
2011-01-01	51.1563472560353
2012-01-01	51.2180737594369
2013-01-01	51.3249945941595
2014-01-01	51.4760155873161
2015-01-01	51.6682897969208
2016-01-01	51.8356767913506
2017-01-01	52.0514995634813