Year Percent 1971 4.1811 1972 3.2081 1973 4.86208 1974 2.80874 1975 -2.39534 1976 3.078 1977 2.40572 1978 2.84575 1979 2.32608 1980 0.35474 1981 -0.63433 1982 0.72667 1983 -0.50151 1984 0.00026 1985 0.56939 1986 1.72563 1987 2.02436 1988 4.3732 1989 3.89003 1990 2.20065 1991 0.3843 1992 0.55538 1993 -1.81805 1994 1.24477 1995 1.23875 1996 0.20956 1997 1.30815 1998 2.61018 1999 2.40072 2000 2.99686 2001 1.30985 2002 0.19361 2003 0.15441 2004 1.29857 2005 0.45109 2006 3.17172 2007 12.28825 2008 7.72348