1961

6.8

1990

7.0

1966

7.9

1982

5.6

1992

7.4

1976

6.6

1973

6.0

1975

7.5

1979

6.2

1974

5.0

1999

6.7

2010

7.3

1972

4.0

1992

6.3

1974

6.1

1968

6.2

1988

6.0

1970

4.6