Year	Percent
1960-01-01	24.274500000000000
1961-01-01	23.152300000000000
1962-01-01	21.174300000000000
1963-01-01	19.937700000000000
1964-01-01	19.387900000000000
1965-01-01	18.405500000000000
1966-01-01	18.058300000000000
1967-01-01	17.952300000000000
1968-01-01	16.860400000000000
1969-01-01	16.323500000000000
1970-01-01	16.090999999999998
1971-01-01	15.650300000000000
1972-01-01	17.313400000000000
1973-01-01	20.351300000000000
1974-01-01	21.660300000000000
1975-01-01	20.196200000000000
1976-01-01	19.613800000000000
1977-01-01	22.084100000000000
1978-01-01	23.059900000000000
1979-01-01	24.578700000000000
1980-01-01	23.882900000000000
1981-01-01	23.300500000000000
1982-01-01	23.828100000000000
1983-01-01	23.773700000000000
1984-01-01	23.583800000000000
1985-01-01	26.323300000000000
1986-01-01	29.316700000000000
1987-01-01	32.299400000000000
1988-01-01	48.073600000000000
1989-01-01	64.424400000000000
1990-01-01	67.107300000000000
1991-01-01	69.006400000000000
1992-01-01	71.151500000000000
1993-01-01	72.750700000000000
1994-01-01	72.449500000000000
1995-01-01	74.113300000000000
1996-01-01	78.071900000000000
1997-01-01	81.595900000000000
1998-01-01	81.560300000000000
1999-01-01	82.489200000000000
2000-01-01	81.635600000000000
2001-01-01	80.988300000000000
2002-01-01	78.821300000000000
2003-01-01	78.214400000000000
2004-01-01	78.195500000000000
2005-01-01	77.936900000000000
2006-01-01	81.909800000000000
2007-01-01	86.059300000000000
2008-01-01	88.426500000000000
2009-01-01	90.626400000000000
2010-01-01	91.519800000000000