1957

7.9

2010

6.1

1980

6.3

1974

6.1

1996

6.0

1989

7.1

1982

7.6

1970

8.2

1968

6.5

1988

5.8

1965

6.9

2002

7.5

2006

5.8

1989

7.0

1949

7.9

2002

5.4

1997

6.2

1979

6.6

2010

6.7

1993

6.0