1997

6.7

2001

6.0

1981

6.5

1994

7.0

1999

6.1

1983

6.2

1960

7.6

1998

7.2

1998

7.1

1966

6.8

1983

6.3

1974

7.5

2007

6.7

1973

7.5

1989

6.3

1991

6.5

1992

6.0

1977

6.0

1982

6.0

2002

6.2