Year	Percent of Total
1960-01-01	43.4623908132503
1961-01-01	43.5974843645298
1962-01-01	43.5271783321823
1963-01-01	43.3588614262802
1964-01-01	43.2270778659167
1965-01-01	43.1845625948996
1966-01-01	43.3955370055550
1967-01-01	43.6267623300386
1968-01-01	43.8471363523952
1969-01-01	43.9951868769281
1970-01-01	44.0474469031579
1971-01-01	44.2560951300748
1972-01-01	44.3387603004128
1973-01-01	44.3356775020863
1974-01-01	44.2961563426955
1975-01-01	44.2455436387415
1976-01-01	44.3232322096167
1977-01-01	44.3620991232374
1978-01-01	44.3682494621748
1979-01-01	44.3470872268433
1980-01-01	44.3079554314746
1981-01-01	44.3962072148629
1982-01-01	44.4480564604294
1983-01-01	44.4675012796287
1984-01-01	44.4622477226657
1985-01-01	44.4384634188245
1986-01-01	44.6587743658954
1987-01-01	44.8376715638250
1988-01-01	44.9620986967300
1989-01-01	44.9975274849590
1990-01-01	44.9128917734206
1991-01-01	45.5779543804122
1992-01-01	46.1764032499386
1993-01-01	46.7074232820606
1994-01-01	47.1958807860006
1995-01-01	47.6512373635143
1996-01-01	47.1151615384393
1997-01-01	46.5345501130846
1998-01-01	45.9168301944376
1999-01-01	45.2745586889960
2000-01-01	44.6389281304739
2001-01-01	43.7908692971711
2002-01-01	42.9783721140617
2003-01-01	42.2256849099783
2004-01-01	41.5531395526332
2005-01-01	40.9703988932244
2006-01-01	41.0061800283673
2007-01-01	41.0886006704978
2008-01-01	41.2232471679587
2009-01-01	41.4077656163072
2010-01-01	41.6207832669831
2011-01-01	41.8025159284777