Year Percent 1980-01-01 35.19747000000000000000 1981-01-01 37.60156000000000000000 1982-01-01 24.46568000000000000000 1983-01-01 24.85639000000000000000 1984-01-01 24.69481000000000000000 1985-01-01 26.64367000000000000000 1986-01-01 27.07202999999999800000 1987-01-01 28.86277000000000000000 1988-01-01 30.75815999999999700000 1989-01-01 37.37335000000000000000 1990-01-01 0.38812520000000000000 1991-01-01 0.74780269999999990000 1992-01-01 2.05538500000000000000 1993-01-01 1.98087700000000000000 1994-01-01 1.96308100000000000000 1995-01-01 3.32710700000000000000 1996-01-01 1.89793700000000000000 1997-01-01 0.50194259999999990000 1998-01-01 1.64398100000000010000 1999-01-01 2.69067500000000000000 2000-01-01 2.47159000000000000000 2001-01-01 1.11548500000000000000 2002-01-01 0.37425010000000000000 2003-01-01 0.06371050000000000000 2004-01-01 0.00011030000000000000 2005-01-01 0.00011030000000000000 2006-01-01 0.00000426000000000000 2007-01-01 0.00030160000000000000 2008-01-01 0.00047910000000000004 2009-01-01 0.00046540000000000000 2010-01-01 0.00023100000000000000