1947

3.9

1948

3.8

1949

5.9

1950

5.3

1951

3.3

1952

3

1953.

2.9

1954

5.5

1955

4.4

1956

4.1

1957

4.3

1958

6.8

1959

5.5

1960.

5.5

1961

6.7

1962.

5.5

1963

5.7

1964

5.2

1965

4.5

1966

3.8

1967

3.8

1968

3.6

1969

3.5

1970

4.9

1971

5.9

1972.

5.6

1973.

4.9

1974

5.6

1975

8.5

1976

7.7

1977

7.1

1978.

6.1

1979

5.8

1980

7.1

1981

7.6

1982

9.7

1983

9.6

1984

7.5

1985

7.2

1986.

7

1987

6.2

1988

5.5

1989

5.3

1990.

5.6

1991

6.8

1992

7.5

1993

6.9

1994.

6.1

1995

5.6

1996

5.4

1997.

4.9

1998.

4.5

1999.

4.2

2000.

4

2001

4.7

2002

5.8

2003.

6

Average

 5.6