1975

7.3

2005

7.0

1988

7.1

2000

7.9

2020

7.1

2005

6.7

1991

6.4

2000

6.4

1999

7.6

1966

5.9

1992

5.4

1978

7.4

1986

6.0

1960

7.0

1990

7.4

2017

7.0

1982

5.9

1939

0.0

1952

7.4

2006

6.6