1978

7.2

2005

7.0

1997

7.8

1996

6.8

1993

8.1

1996

7.0

1989

6.7

2001

7.4

1978

7.1

1986

6.2

1991

7.7

1982

5.7

2001

8.3

2011

6.5

1951

7.9

1988

5.8

1978

5.0

1976

7.0

1982

7.2

1966

6.6