Year	Percent of Total
1960-01-01	57.4599536550520
1961-01-01	57.0675903577428
1962-01-01	56.7521766139191
1963-01-01	56.5035884933625
1964-01-01	56.3239708113004
1965-01-01	56.2134552134752
1966-01-01	55.8454677532927
1967-01-01	55.5881142998121
1968-01-01	55.4199062975690
1969-01-01	55.3243463414090
1970-01-01	55.2900434131401
1971-01-01	54.9057759366898
1972-01-01	54.6232023393992
1973-01-01	54.4214522513722
1974-01-01	54.2773273480768
1975-01-01	54.1750356404272
1976-01-01	53.9596732940426
1977-01-01	53.8227976215578
1978-01-01	53.7422378273733
1979-01-01	53.6978465907170
1980-01-01	53.6748718430087
1981-01-01	53.5872510489829
1982-01-01	53.5472729948686
1983-01-01	53.5433901493501
1984-01-01	53.5755862784477
1985-01-01	53.6481221092144
1986-01-01	53.3375083704674
1987-01-01	53.1051696328891
1988-01-01	52.9425967305824
1989-01-01	52.8356914199622
1990-01-01	52.7758879916184
1991-01-01	52.7824697209337
1992-01-01	52.8693487675427
1993-01-01	53.0190914057554
1994-01-01	53.2177667879559
1995-01-01	53.4564137621254
1996-01-01	53.4583146211633
1997-01-01	53.5102545724587
1998-01-01	53.6112759685160
1999-01-01	53.7631633060502
2000-01-01	53.9626246276284
2001-01-01	53.8634566070743
2002-01-01	53.8442148299268
2003-01-01	53.8866529454387
2004-01-01	53.9693605679456
2005-01-01	54.0823564467249
2006-01-01	53.9261661428383
2007-01-01	53.8203611020160
2008-01-01	53.7683648817389
2009-01-01	53.7798434686654
2010-01-01	53.8628196986642
2011-01-01	53.4947308548211
2012-01-01	53.1771666589465
2013-01-01	52.9245255134118
2014-01-01	52.7410909174663
2015-01-01	52.6217637095533
2016-01-01	52.8398098559163
2017-01-01	53.1493556667840