1959

6.1

1995

5.6

1989

5.5

1994

6.2

1987

5.2

1975

6.4

1952

6.7

1984

5.7

1985

6.0

1995

4.6

2005

5.2

2012

6.2

1988

6.2

1998

6.5

1921

6.8

1977

7.0

1965

7.2

1995

8.7

2006

6.7

2010

6.4