1953

6.8

1989

5.7

1974

7.0

1965

5.7

1979

6.7

1969

4.4

1977

7.0

1961

6.4

1997

6.2

2007

6.4

1956

7.0

2007

6.7

1936

4.7

2002

6.0

1991

6.8

1984

5.9

2005

7.1

2017

6.6

1982

5.0

2006

7.8