Year Years 1970 4.5 1971 4.074 1972 4.52 1973 3.401 1974 3.228 1975 2.244 1976 1.239 1977 0.4329 1978 0.1284 1979 -0.00409 1980 0.0934 1981 -2.176 1982 -2.703 1983 -2.717 1984 -2.43 1985 -3.132 1986 -4.096 1987 -3.876 1988 -3.657 1989 -3.771 1990 -3.641 1991 -2.127 1992 -2.524 1993 -1.801 1994 -1.511 1995 -0.3727 1996 0.103 1997 0.05074 1998 0.08317 1999 -0.5722 2000 -0.9619 2001 -1.266 2002 -1.21 2003 -0.33 2004 -1.323