Year	Percent of Total
1960-01-01	51.0743875878483
1961-01-01	50.8323359808508
1962-01-01	50.3524098927999
1963-01-01	49.8260905147721
1964-01-01	49.4978905460812
1965-01-01	49.4391485777727
1966-01-01	49.4271112013137
1967-01-01	49.6262362612973
1968-01-01	49.9717480266425
1969-01-01	50.3407013461858
1970-01-01	50.7203203594277
1971-01-01	50.3236298061441
1972-01-01	49.8956627821118
1973-01-01	49.4429282388827
1974-01-01	48.9339906524105
1975-01-01	48.3323831242873
1976-01-01	48.5773304755692
1977-01-01	48.7663565539672
1978-01-01	48.8977162792061
1979-01-01	49.0035435861091
1980-01-01	49.1132613343567
1981-01-01	49.4394529697066
1982-01-01	49.7047105394637
1983-01-01	49.9925630283349
1984-01-01	50.3700144161461
1985-01-01	50.8647853791751
1986-01-01	51.0415245372265
1987-01-01	51.3630304376805
1988-01-01	51.7544908227470
1989-01-01	52.0878723788673
1990-01-01	52.3164920949642
1991-01-01	52.3699632587374
1992-01-01	52.3571928648201
1993-01-01	52.3870918082630
1994-01-01	52.5755018527773
1995-01-01	52.9296366543940
1996-01-01	53.3827438529130
1997-01-01	53.8699747470093
1998-01-01	54.4725512296975
1999-01-01	55.1838317132893
2000-01-01	55.9609799687244
2001-01-01	56.0705454206131
2002-01-01	56.2809044427619
2003-01-01	56.5533253445177
2004-01-01	56.8602981881644
2005-01-01	57.1961279144224
2006-01-01	57.6056924416184
2007-01-01	58.0264184700889
2008-01-01	58.4400543655124
2009-01-01	58.8514813389765
2010-01-01	59.2553273625695
2011-01-01	59.8097962655120
2012-01-01	60.3354492140324
2013-01-01	60.8223563672832
2014-01-01	61.2430899389511
2015-01-01	61.5791943159729
2016-01-01	61.8685497012493
2017-01-01	62.0726900629121