Year Percent 1965-01-01 1.5684500000000000 1966-01-01 2.2292099999999997 1967-01-01 2.6313200000000000 1968-01-01 2.4294599999999997 1969-01-01 2.5031500000000000 1970-01-01 1.5480000000000000 1971-01-01 1.5759900000000000 1972-01-01 1.6553000000000000 1973-01-01 2.0436099999999997 1974-01-01 2.3003200000000000 1975-01-01 3.0380000000000003 1976-01-01 3.7061000000000000 1977-01-01 3.4767900000000003 1978-01-01 4.1804400000000000 1979-01-01 5.4287600000000000 1980-01-01 7.0639800000000000 1981-01-01 7.9941699999999996 1982-01-01 7.7760100000000000 1983-01-01 6.8968800000000000 1984-01-01 7.6067800000000005 1985-01-01 8.1774800000000010 1986-01-01 8.1888899999999990 1987-01-01 8.6322300000000000 1988-01-01 9.7844100000000010 1989-01-01 10.2527000000000000 1990-01-01 10.5015000000000000 1991-01-01 12.1798000000000000 1992-01-01 10.1302000000000000 1993-01-01 4.9996000000000000 1994-01-01 2.9860500000000000 1995-01-01 2.6403900000000000 1996-01-01 2.6505799999999997 1997-01-01 3.4188699999999996 1998-01-01 4.5146500000000000 1999-01-01 5.5668100000000000 2000-01-01 5.7608600000000000 2001-01-01 4.7121800000000000 2002-01-01 3.6117600000000000 2003-01-01 3.1695100000000000 2004-01-01 2.8017100000000000 2005-01-01 3.3561099999999997 2006-01-01 3.4576700000000000