1980

5.3

2014

5.9

2003

7.2

1983

5.5

2000

8.1

1977

5.5

1988

6.1

1996

6.5

1986

6.3

1996

6.1

1984

7.2

2006

6.9

2006

7.5

2008

6.8

2004

7.3

1990

6.0

1991

6.2

2013

5.8

1985

5.9

2003

6.5