Year	Percent of Total
1960-01-01	53.7749438100138
1961-01-01	53.6575832030377
1962-01-01	53.7455644050094
1963-01-01	53.9347982759089
1964-01-01	54.0941113702673
1965-01-01	54.1714306569619
1966-01-01	53.9633766913712
1967-01-01	53.7418976421033
1968-01-01	53.5363174815612
1969-01-01	53.4059420418819
1970-01-01	53.3727988308264
1971-01-01	53.1614835382998
1972-01-01	53.0786978207417
1973-01-01	53.0845834435873
1974-01-01	53.1296216252079
1975-01-01	53.1875537400679
1976-01-01	53.0942395053154
1977-01-01	53.0439548614088
1978-01-01	53.0304065293087
1979-01-01	53.0470844233005
1980-01-01	53.0845427031196
1981-01-01	52.9768214159720
1982-01-01	52.9109835158766
1983-01-01	52.8811850323852
1984-01-01	52.8785034078217
1985-01-01	52.8952825326326
1986-01-01	52.6471470450046
1987-01-01	52.4449715133180
1988-01-01	52.3003059180185
1989-01-01	52.2454636104058
1990-01-01	52.3093902279599
1991-01-01	51.5703817066304
1992-01-01	50.9004412903044
1993-01-01	50.3010764276889
1994-01-01	49.7503924071843
1995-01-01	49.2411555521900
1996-01-01	49.7128237611664
1997-01-01	50.2372404194410
1998-01-01	50.8063803279116
1999-01-01	51.4072016674626
2000-01-01	52.0086500799782
2001-01-01	52.8269801128013
2002-01-01	53.6205966902919
2003-01-01	54.3619299327362
2004-01-01	55.0272208505469
2005-01-01	55.6046386413529
2006-01-01	55.5247220806915
2007-01-01	55.4064543840945
2008-01-01	55.2438716676794
2009-01-01	55.0387510573426
2010-01-01	54.8120632954059
2011-01-01	54.5900833353819