1962

7.0

1963

7.1

1964

7.4

1962

7.9

1967

6.6

1969

6.6

1974

6.4

1977

6.8

1981

6.5

1985

6.2

1987

6.5

1994

6.8

1997

6.4

1995

7.6

1993

7.4

2007

6.2

1971

7.2

2009

6.1

1973

6.5

1991

8.3