1983

7.4

2007

6.2

1979

6.3

1973

6.3

1981

6.9

1963

7.7

2001

7.5

2019

7.1

2002

6.1

2015

5.9

2007

4.9

1978

7.5

1993

6.5

1991

4.7

1997

6.8

1977

7.0

1980

6.6

1985

7.4

2006

6.1