1961

6.6

1973

6.2

1954

7.9

1969

6.6

1971

6.4

1977

6.8

1993

7.2

1987

7.6

1990

8.5

1996

6.6

2002

7.1

2005

7.8

1988

7.8

2002

6.7

2005

6.3

1972

7.1

2002

7.3

1987

8.1

1999

6.5

2001

6.7