1979

6.1

2008

7.3

2008

5.9

2006

5.1

1985

6.2

1983

6.1

1974

7.2

1975

8.4

2013

7.9

1998

7.8

1981

8.1

2005

7.5

2009

7.1

2017

7.2

2013

7.4

1979

6.8

1973

7.1

1973

8.0

1966

7.7

1983

6.3