1972

6.8

1994

7.1

1979

6.7

1985

6.7

1979

6.1

1980

6.8

1959

7.5

1986

6.0

1992

7.1

2004

7.0

1976

6.0

1985

7.4

1999

5.7

1959

5.0

2005

7.8

1980

5.0

1979

6.5

2001

6.8

1997

8.6

2006

8.2