Year Percent 1960-01-01 11.8307000000000000 1961-01-01 9.8435300000000000 1962-01-01 7.7622800000000005 1963-01-01 7.1274700000000000 1964-01-01 5.6164800000000000 1965-01-01 5.6265800000000010 1966-01-01 6.0478900000000000 1967-01-01 5.5730500000000000 1968-01-01 5.5567800000000010 1969-01-01 6.3840699999999995 1970-01-01 8.4941100000000010 1971-01-01 8.8542700000000000 1972-01-01 9.3922300000000000 1973-01-01 10.7865000000000000 1974-01-01 11.2642000000000000 1975-01-01 12.7828000000000000 1976-01-01 13.6238000000000000 1977-01-01 14.9182000000000000 1978-01-01 16.3384000000000000 1979-01-01 16.7460000000000000 1980-01-01 16.4380000000000000 1981-01-01 16.4696000000000000 1982-01-01 19.4287000000000000 1983-01-01 23.1727000000000000 1984-01-01 28.8276000000000000 1985-01-01 31.5868000000000000 1986-01-01 30.9278000000000000 1987-01-01 28.5929000000000000 1988-01-01 20.1804000000000000 1989-01-01 21.6282000000000000 1990-01-01 22.0152000000000000 1991-01-01 21.9620000000000000 1992-01-01 22.2243000000000000 1993-01-01 26.9365000000000000 1994-01-01 25.5865000000000000 1995-01-01 27.4287000000000000 1996-01-01 26.1896000000000000 1997-01-01 26.7622000000000000 1998-01-01 27.9798000000000000 1999-01-01 31.1981000000000000 2000-01-01 32.8568000000000000 2001-01-01 39.3621000000000000 2002-01-01 43.1323000000000000 2003-01-01 52.4089000000000000 2004-01-01 46.1234000000000000 2005-01-01 42.0364000000000000 2006-01-01 41.9520000000000000 2007-01-01 40.1039000000000000 2008-01-01 43.4576000000000000 2009-01-01 48.1432000000000000 2010-01-01 48.8395000000000000