Year	Percent of Total
1960-01-01	54.4710142590501
1961-01-01	54.1630242186793
1962-01-01	53.9258128124341
1963-01-01	53.7479661253755
1964-01-01	53.6235156648683
1965-01-01	53.5466069997420
1966-01-01	53.2626498732164
1967-01-01	53.0617402852487
1968-01-01	52.9292682661958
1969-01-01	52.8578316110348
1970-01-01	52.8462054167889
1971-01-01	52.6374075956756
1972-01-01	52.5028738570244
1973-01-01	52.4268223175146
1974-01-01	52.3900916082281
1975-01-01	52.3809095206408
1976-01-01	52.2306528403546
1977-01-01	52.1408556760670
1978-01-01	52.0969104733801
1979-01-01	52.0922631507318
1980-01-01	52.1235224997415
1981-01-01	51.9833646622876
1982-01-01	51.9192175330600
1983-01-01	51.9145912908373
1984-01-01	51.9533478089922
1985-01-01	52.0257463228883
1986-01-01	51.9486542862205
1987-01-01	51.9415040243521
1988-01-01	51.9888597218888
1989-01-01	52.0791618638797
1990-01-01	52.2056477770239
1991-01-01	52.2537513310546
1992-01-01	52.3502894114652
1993-01-01	52.4897911620603
1994-01-01	52.6707960273581
1995-01-01	52.8917719933106
1996-01-01	52.9682917591272
1997-01-01	53.0994752992723
1998-01-01	53.2721118442085
1999-01-01	53.4704397559663
2000-01-01	53.6830876987657
2001-01-01	53.7958330861523
2002-01-01	53.9360585441947
2003-01-01	54.0935967131811
2004-01-01	54.2635565400939
2005-01-01	54.4465880880504
2006-01-01	54.5323269953331
2007-01-01	54.6464998254582
2008-01-01	54.7867591329092
2009-01-01	54.9503783118933
2010-01-01	55.1355264038523
2011-01-01	55.3265719536800
2012-01-01	55.5436558557182
2013-01-01	55.7823982318665
2014-01-01	56.0393667348635
2015-01-01	56.3110750085875
2016-01-01	56.5480914155343
2017-01-01	56.8033740979006