1963

7.4

1969

7.1

1959

5.9

1964

5.9

1970

5.7

1959

6.4

1961

6.2

1964

6.4

1966

5.6

1970

4.6

1967

6.6

1973

6.1

1967

5.3

1976

2.8

1960

6.0

1957

6.0

1962

7.3

1955

6.5

1960

5.6

1973

5.0

1955

7.6

1965

5.7

1956

6.0

1967

6.2

1953

5.8

1959

3.1

1960

7.0

1962

7.2

1967

6.1

1960

6.1

1970

5.4

1953

6.1

1956

6.3