1981

7.0

2000

9.8

1990

6.0

1988

6.2

2001

6.4

1953

7.1

1990

6.4

1965

7.5

1986

5.8

2004

6.1

2007

6.9

1995

7.2

1976

6.7

1970

8.2

1988

6.5

1970

6.1

1995

6.5

1997

6.6

2009

6.3

1949

7.7