1998

7.4

1999

7.5

2001

6.7

2013

6.5

2005

5.9

2007

6.1

1978

5.7

1997

6.5

1992

6.0

1996

6.5

2016

6.0

2016

6.2

2007

6.6

2016

5.5

1970

2.0

1957

10.0

2005

5.5

1985

8.0

1979

7.3

2007

0.0