1980

6.6

1982

6.4

2001

7.9

1994

6.8

1968

7.3

1962

7.2

1970

7.2

1979

7.1

2000

6.3

1994

6.0

1938

3.0

1956

7.7

2009

5.7

1964

7.5

1983

6.5

2005

6.7

1976

7.0

1960

6.6

2002

7.0

2015

6.8