Year Years 1970 7.909 1971 8.339 1972 8.18 1973 7.272 1974 6.054 1975 4.719 1976 4.984 1977 6.292 1978 7.024 1979 6.573 1980 6.668 1981 6.624 1982 6.042 1983 5.46 1984 6.336 1985 6.39 1986 6.184 1987 6.09 1988 5.863 1989 5.549 1990 5.142 1991 5.031 1992 5.412 1993 5.519 1994 5.244 1995 5.274 1996 4.545 1997 3.732 1998 2.074 1999 1.818 2000 2.156 2001 1.54 2002 1.038 2003 0.7686 2004 1.08