Year Percent 1980-01-01 0.35123800000000000 1981-01-01 0.34084400000000000 1982-01-01 0.39668400000000004 1983-01-01 0.42101000000000005 1984-01-01 0.43172700000000000 1985-01-01 0.30660400000000000 1986-01-01 0.40369600000000000 1987-01-01 0.42233200000000000 1988-01-01 0.42233200000000000 1989-01-01 0.42233200000000000 1990-01-01 0.42233200000000000 1991-01-01 0.42233200000000000 1992-01-01 0.42233200000000000 1993-01-01 0.07727800000000000 1994-01-01 0.22991599999999998 1995-01-01 0.32388700000000000 1996-01-01 1.02587000000000000 1997-01-01 1.05418000000000000 1998-01-01 0.44307799999999997 1999-01-01 0.49302799999999997 2000-01-01 0.54546400000000010 2001-01-01 0.45919799999999994