Year Years 1960 6.213 1961 6.428 1962 6.013 1963 6.481 1964 6.62 1965 5.325 1966 4.905 1967 4.44 1968 4.413 1969 4.47 1970 3.755 1971 2.151 1972 3.519 1973 3.095 1974 3.011 1975 3.349 1976 3.693 1977 3.571 1978 3.88 1979 3.35 1980 4.09 1981 4.982 1982 3.694 1983 2.233 1984 1.142 1985 0.3066 1986 -1.549 1987 -1.917 1988 -3.004 1989 -3.355 1990 -3.677 1991 -3.802 1992 -3.23 1993 -2.182 1994 -0.8363 1995 0.2981 1996 1.506 1997 1.612 1998 1.818 1999 3.278 2000 4.97 2001 4.568 2002 3.405 2003 6.814